KR20220077810A - ferroelectric ferromagnetic composite laminated structure controlling output voltage - Google Patents

Abstract

The present invention provides a ferroelectric-ferromagnetic composite laminate structure in which an output voltage is controlled using a self-bias magneto-electric effect without an external DC bias magnetic field. A ferroelectric-ferromagnetic composite laminate structure according to an embodiment of the present invention includes a composite layer including a first magnetostrictive layer, a piezoelectric layer positioned on the first magnetostrictive layer, and a second magnetostrictive layer positioned on the piezoelectric layer; a first magnet member disposed on one end of the composite layer; and a second magnet member disposed at the other end of the composite layer.

Description

ferroelectric ferromagnetic composite laminated structure controlling output voltage

The technical idea of the present invention relates to a magnetic material, and more particularly, to a ferroelectric-ferromagnetic composite laminate structure in which an output voltage is controlled.

A multiferroic magnetoelectric structure is composed of a piezoelectric material and a magnetostrictive material, and is applied in various technical fields including magnetic sensors, voltage regulation inductors, data storage elements, spintronics, energy harvesters, and the like. The magnetoelectric effect of this magnetoelectric structure is due to the interfacial coupling between the piezoelectric material and the magnetostrictive material. The transfer of mechanical strain between the piezoelectric material and the magnetostrictive material causes a change in the electric polarization of the piezoelectric material or a change in the magnetic flux of the magnetostrictive material, and the effect is known to be greatest in the 2-2 layered structure.

The overall performance of a magnetostrictive device using magnetostrictive properties is determined by the deformation of the magnetostrictive material. Since the deformation of the magnetostrictive material depends on the DC bias magnetic field, an external DC bias magnetic field may be required to achieve excellent magnetostrictive performance. However, the requirement for an external DC bias magnetic field has a disadvantage of generating electromagnetic interference or increasing the size of the device. Accordingly, there is a need for a self-biased magnetoelectric structure that does not require an external DC bias magnetic field.

An object of the present invention is to provide a ferroelectric-ferromagnetic composite laminate structure in which an output voltage is controlled using a self-bias magneto-electric effect without an external DC bias magnetic field.

However, these tasks are exemplary, and the technical spirit of the present invention is not limited thereto.

The ferroelectric-ferromagnetic composite laminate structure according to the technical idea of the present invention for achieving the above technical problem includes a first magnetostrictive layer, a piezoelectric layer located on the first magnetostrictive layer, and a second magnetostrictive layer located on the piezoelectric layer. a composite layer comprising; a first magnet member disposed on one end of the composite layer; and a second magnet member disposed at the other end of the composite layer.

In an embodiment of the present invention, the first magnet member and the second magnet member may be disposed above the second magnetostrictive layer.

In an embodiment of the present invention, the first magnet member may be disposed above the second magnetostrictive layer, and the second magnet member may be disposed below the first magnetostrictive layer.

In an embodiment of the present invention, in the first magnet member, a first N pole and a first S pole are sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer, and the second magnet member includes , a second S pole and a second N pole may be sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer.

In an embodiment of the present invention, in the first magnet member, a first S pole and a first N pole are sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer, and the second magnet member includes , a second N pole and a second S pole may be sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer.

In an embodiment of the present invention, in the first magnet member, a first N pole and a first S pole are sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer, and the second magnet member includes , a second S pole and a second N pole may be sequentially disposed in a direction perpendicular to the lower surface of the first magnetostrictive layer.

In an embodiment of the present invention, in the first magnet member, a first S pole and a first N pole are sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer, and the second magnet member includes , a second N pole and a second S pole may be sequentially disposed in a direction perpendicular to the lower surface of the first magnetostrictive layer.

In an embodiment of the present invention, in the first magnet member, a first S pole and a first N pole are sequentially disposed in a horizontal direction with respect to the upper surface of the second magnetostrictive layer, and the second magnet member includes , a second S pole and a second N pole may be sequentially disposed in a horizontal direction with respect to an upper surface of the second magnetostrictive layer.

In an embodiment of the present invention, in the first magnet member, a first S pole and a first N pole are sequentially disposed in a horizontal direction with respect to the upper surface of the second magnetostrictive layer, and the second magnet member includes , a second S pole and a second N pole may be sequentially disposed in a horizontal direction with respect to a lower surface of the first magnetostrictive layer.

In one embodiment of the present invention, a fixing member located in the center of the composite layer to fix the composite layer; may further include.

In an embodiment of the present invention, the first magnetostrictive layer and the second magnetostrictive layer may include at least one from the group consisting of an iron-silicon-boron-based alloy, nickel, iron, cobalt, and alloys thereof. can

In an embodiment of the present invention, the piezoelectric layer may include Pb(Zr,Ti)O ₃ .

In an embodiment of the present invention, the first magnet member and the second magnet member may include at least one from the group consisting of neodymium (Nd), iron, cobalt, nickel, and alloys thereof.

The ferroelectric-ferromagnetic composite laminate structure according to the technical idea of the present invention for achieving the above technical problem includes a first magnetostrictive layer, a piezoelectric layer located on the first magnetostrictive layer, and a second magnetostrictive layer located on the piezoelectric layer. a composite layer comprising; a first magnet member spaced apart from one side of the composite layer; a first rotating member functioning as a rotating shaft for rotating the first magnet member; and a second magnet member spaced apart from the other side of the composite layer.

In one embodiment of the present invention, a second rotating member functioning as a rotation shaft for rotating the second magnet member; may further include.

The ferroelectric-ferromagnetic composite laminate structure in which the output voltage is controlled using self-bias magnetoelectricity according to the technical concept of the present invention is a magnetostrictive-ferromagnetic composite laminate structure by applying a pair of magnet members composed of permanent magnets, strong from the center fixed by the magnetostrictive-piezoelectric laminate structure. A self-biased magnetoelectric (SME) response can be implemented.

In the ferroelectric-ferromagnetic composite laminate structure, an asymmetric laminate structure composed of two different magnetostrictive layers (metglass, nickel) having opposite positive and negative magnetostrictive coefficients, respectively, was applied to promote structural bending resonance. The effect of changing the arrangement of magnet members on the self-bias magnetoelectric response was analyzed. The highest self-bias magnetoelectric effect was observed when all the magnet members were disposed on the metglass layer, and their magnetization direction was perpendicular to the surface of the metglass layer. From these results, it is analyzed that magnetic domains parallel and non-parallel to the external magnetic field contribute to the overall magnetostriction. The manufactured self-biased magneto-electrical laminated structure exhibited a strong self-biased magneto-electrical voltage coefficient ranging from 14.11 Vcm ^-1 Oe ^-1 to 52.35 Vcm ^-1 Oe ^-1 , depending on the direction of the magnetic field of the magnet members.

Based on such a high self-bias magnetoelectric voltage output value and their controllability, the ferroelectric-ferromagnetic composite laminate structure can be used for precise magnetic field sensors, magnetic energy harvesters, and electric and magnetic field adjustment devices.

The above-described effects of the present invention have been described by way of example, and the scope of the present invention is not limited by these effects.

1 is a schematic diagram illustrating a ferroelectric-ferromagnetic composite laminate structure according to an embodiment of the present invention.
2 is a schematic diagram illustrating an arrangement of a magnet member in a ferroelectric-ferromagnetic composite laminate structure according to an embodiment of the present invention.
3 is a schematic diagram illustrating a ferroelectric-ferromagnetic composite laminate structure according to an embodiment of the present invention.
4 is a photograph showing a measuring device for measuring magnetoelectric voltage output of a ferroelectric-ferromagnetic composite laminate structure according to an embodiment of the present invention.
5 is a graph showing a phase angle spectrum of a ferroelectric-ferromagnetic composite laminate structure according to an embodiment of the present invention.
6 is a photograph showing the bending behavior of a ferroelectric-ferromagnetic composite laminate structure according to an embodiment of the present invention.
7 is a graph showing a magnetoelectric voltage coefficient with respect to a DC bias magnetic field of a comparative example for comparison with a ferroelectric-ferromagnetic composite laminate structure according to an embodiment of the present invention.
8 is a graph showing a magnetoelectric voltage coefficient with respect to a DC bias magnetic field of a ferroelectric-ferromagnetic composite laminate structure according to Example 1 of the present invention.
9 is a graph showing the magnetoelectric voltage coefficient with respect to the DC bias magnetic field of the ferroelectric-ferromagnetic composite laminate structure according to Example 2 of the present invention.
10 is a schematic diagram illustrating a magnetic field distribution formed in a ferroelectric-ferromagnetic composite laminate structure according to Examples 1 and 2 of the present invention.
11 is a graph showing magnetoelectric voltage coefficients with respect to a DC bias magnetic field of a ferroelectric-ferromagnetic composite laminate structure according to Examples 3 and 4 of the present invention.
12 is a schematic diagram showing a magnetic field distribution formed in a ferroelectric-ferromagnetic composite laminate structure according to Examples 3 and 4 of the present invention.
13 is a schematic diagram illustrating a magnetic field and magnetization behavior formed in a magnetostrictive layer in a ferroelectric-ferromagnetic composite laminate structure according to Examples 1 and 3 of the present invention.
14 is a schematic diagram illustrating a change in magnetization of a magnetostrictive layer when a minute DC bias magnetic field is applied in the ferroelectric-ferromagnetic composite laminate structure of the present invention.
15 is a graph showing magnetoelectric voltage coefficients with respect to a DC bias magnetic field under an alternating magnetic field of a ferroelectric-ferromagnetic composite laminate structure according to Examples 1 and 3 of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention are provided to more completely explain the technical idea of the present invention to those of ordinary skill in the art, and the following examples may be modified in various other forms, The scope of the technical idea is not limited to the following examples. Rather, these embodiments are provided so as to more fully and complete the present disclosure, and to fully convey the technical spirit of the present invention to those skilled in the art. In this specification, the same reference numerals refer to the same elements throughout. Furthermore, various elements and regions in the drawings are schematically drawn. Accordingly, the technical spirit of the present invention is not limited by the relative size or spacing drawn in the accompanying drawings.

The technical idea of the present invention is a ferroelectric-ferromagnetic composite laminate that can effectively convert a magnetic field into an electric field using the self-bias magneto-electric effect without an external DC bias magnetic field, and can easily control the output voltage or electric field even under the same magnetic field. provide a structure.

In the absence of a DC bias magnetic field, a self-biased magnetoelectric (SME) effect is determined by magnetoelectric coupling in a state in which an external alternating magnetic field (H _AC ) is applied. The expression form of the self-bias magnetoelectric effect is proposed in the following five forms according to experiments and theories. Specifically, there are self-biased magnetoelectricity using a ferromagnetic material having a functional gradient, self-biased magnetoelectricity through exchange bias, self-biased magnetoelectricity based on magnetostrictive hysteresis, self-biased magnetoelectricity through built-in stress, and nonlinear self-biased magnetoelectricity.

In order to implement such a self-biased magnetoelectricity, it is possible to use an exchange bias (EB) of the magnetostrictive layer. The exchange bias means that the magnetic hysteresis loop moves along the magnetic field axis in the graph, and in general, a magnetic material including a ferromagnetic phase and a soft magnetic phase is cooled to below the antiferromagnetic Neel temperature in a state where an appropriate magnetic field is applied. observed when The magnetization movement of the ferromagnetic layer by the exchange bias field in the composite laminate structure is related to the movement of the magnetostrictive strain (λ) with respect to the DC bias magnetic field (H _DC ) of the ferromagnetic layer, thus generating a self-bias magnetoelectric response. can do it

Previous studies on the self-bias magnetoelectric effect mediated by exchange bias in magnetoelectric structures have focused on the exchange bias control (ie, reverse magnetoelectric effect) by an external electric field. The self-bias magnetoelectric effect mediated by magnetically controlled exchange bias is important in electrostatic devices such as sensors, regulating transformers and energy harvesters, but little research has been done on it. The reason why the study on self-bias magnetoelectric reaction mediated by exchange bias is insufficient is that it requires special processes such as magnetic field-cooling along with the difficulty of synthesizing heterogeneous ferromagnetic materials, deterioration of exchange bias with time, and thickness of magnetostrictive layer. This is because there are problems such as inverse dependence of

As a simple method similar to the attempt using an exchange bias as described above, a magnetic field may be applied in advance in the magnetostrictive layer by using a permanent magnet in order to move the magnetostriction with respect to the DC bias magnetic field. In the case of using a permanent magnet, it can be easily applied to a desired magnetostrictive material without performing a complicated experimental process. In addition, since a permanent magnet is used, there is an advantage in that device characteristics do not deteriorate over time. Nevertheless, systematic studies to prove this method or to understand the physical mechanism have not been conducted.

In the ferroelectric-ferromagnetic composite laminate structure according to the technical idea of the present invention, a composite layer composed of a magnetostrictive (MS) / piezoelectric (PE) / magnetostrictive layer is formed, and permanent magnets are provided at both ends of the composite layer. It is composed by placing In addition, the ferroelectric-ferromagnetic composite laminate structure is configured to be fixed at a central nodal point, and permanent magnet members are disposed at free ends of both ends. In addition, in order to realize high self-bias magnetoelectric performance, an optimal structure was derived by changing the arrangement of the permanent magnet member.

By the configuration of the magnetostrictive layer/piezoelectric layer/magnetostrictive layer, it is possible to effectively convert an AC magnetic field into an AC voltage or an electric field even in an environment without an external DC magnetic field. In addition, if the polarity is changed by rotating the permanent magnet, the output voltage and the strength of the electric field may be changed. The magnetostrictive layer/piezoelectric layer/magnetostrictive layer may exhibit a strong self-bias magnetoelectric (ME) effect.

The ferroelectric-ferromagnetic composite laminate structure can implement a very high level of self-bias magnetoelectric voltage coefficient of 52.35 Vcm ^-1 Oe ^-1 using a simple laminate structure.

In the present invention, in order to understand the mechanism for the high self-bias magnetoelectric response, the correlation between the magnetoelectric voltage with respect to the DC bias magnetic field, the distribution of the pre-applied magnetic field, and the final magnetization of the magnetostrictive layer was analyzed.

1 is a schematic diagram illustrating a ferroelectric-ferromagnetic composite laminate structure 100 according to an embodiment of the present invention.

Referring to FIG. 1 , a ferroelectric-ferromagnetic composite laminate structure 100 includes a first magnetostrictive layer 120 , a piezoelectric layer 130 positioned on the first magnetostrictive layer 120 , and a first magnetostrictive layer positioned on the piezoelectric layer 130 . a composite layer 110 including two magnetostrictive layers 140 ; a first magnet member 150 disposed on one end of the composite layer 110; and a second magnet member 160 disposed at the other end of the composite layer 110 .

In addition, the ferroelectric-ferromagnetic composite laminate structure 100 may further include a fixing member 170 located in the center of the composite layer 110 to fix the composite layer 110 .

The composite layer 110 may have a sandwich-type stacked structure in which the piezoelectric layer 130 is interposed between the first magnetostrictive layer 120 and the second magnetostrictive layer 140 . The composite layer 110 may have a dimension having a length l that is longer than a width b, and may have a thickness t. In the composite layer 110 , a first magnet member 150 and a second magnet member 160 may be disposed at both ends in the longitudinal direction, respectively.

The first magnetostrictive layer 120 and the second magnetostrictive layer 140 may include a material that generates a magnetostrictive phenomenon, for example, may include a ferromagnetic material, for example, iron such as Metglas. -A silicon-boron-based alloy, nickel (Ni), iron (Fe), cobalt (Co), and may include at least one from the group consisting of alloys thereof. The first magnetostrictive layer 120 and the second magnetostrictive layer 140 may include the same material or different materials. For example, the first magnetostrictive layer 120 may include nickel, and the second magnetostrictive layer 140 may include metglass.

The first magnetostrictive layer 120 and the second magnetostrictive layer 140 may have piezomagnetic coefficients of opposite signs. The first magnetostrictive layer 120 may have a negative piezoelectric coefficient, and the second magnetostrictive layer 140 may have a positive piezoelectric coefficient. Alternatively, the first magnetostrictive layer 120 may have a positive piezoelectric coefficient, and the second magnetostrictive layer 140 may have a negative piezoelectric coefficient. Here, the piezoresistive coefficient q is equal to q = dλ/dH _DC , λ is the magnetostrictive strain, and H _DC is the DC bias magnetic field.

The piezoelectric layer 130 may be interposed between the first magnetostrictive layer 120 and the second magnetostrictive layer 140 . The piezoelectric layer 130 may include a material that generates a piezoelectric phenomenon, for example, a ferroelectric material, for example, Pb(Zr,Ti)O ₃ (PZT).

The first magnet member 150 and the second magnet member 160 may be formed of permanent magnets. However, this is exemplary, and the case where the first magnet member 150 and the second magnet member 160 are made of an electromagnet is also included in the technical concept of the present invention.

The first magnet member 150 and the second magnet member 160 may include a magnetic material, and may include at least one from the group consisting of neodymium (Nd), iron, cobalt, nickel, and alloys thereof. have. The first magnet member 150 and the second magnet member 160 may include the same material or different materials. For example, the first magnet member 150 and the second magnet member 160 may include NdFeB.

The fixing member 170 may perform a function of fixing the composite layer 110 and may include various materials such as a metal material or a polymer material. The composite layer 110 may be fixed at the center by the fixing member 170 , and this may be referred to as a nodal point.

Both ends of the composite layer 110 are free ends, and the first magnet member 150 and the second magnet member 160 including permanent magnets such as NdFeB may be disposed. The magnetic field discharged from the first magnet member 150 and the second magnet member 160 may be combined, and accordingly, the ferroelectric-ferromagnetic composite laminate structure 100 forms a pre-applied magnetic field, and the composite layer ( 110 ), the magnetic field may be applied to the first magnetostrictive layer 120 and the second magnetostrictive layer 140 in the longitudinal direction.

2 is a schematic diagram illustrating an arrangement of a magnet member in a ferroelectric-ferromagnetic composite laminate structure 100 according to an embodiment of the present invention.

Referring to FIG. 2 , the first magnet member so that the linear magnetic field H _PA is induced in the same line with respect to the DC bias magnetic field H _DC through the first magnetostrictive layer 120 and the second magnetostrictive layer 140 . A possible arrangement of 150 and the second magnet member 160 is shown.

Referring to (a) of FIG. 2 , in the ferroelectric-ferromagnetic composite laminate structure 100a , the first magnet member 150 and the second magnet member 160 may be disposed on the upper side of the second magnetostrictive layer 140 . have.

In the first magnet member 150 , a first N pole 151 and a first S pole 152 may be sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer 140 . In the second magnet member 160 , a second S pole 162 and a second N pole 161 may be sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer 140 .

In addition, the arrangement order of the first N pole 151 and the first S pole 152 may be changed, and the arrangement order of the second N pole 161 and the second S pole 162 may be changed with each other. In the first magnet member 150 , a first S pole 152 and a first N pole 151 may be sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer 140 . In the second magnet member 160 , a second N pole 161 and a second S pole 162 may be sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer 140 .

)이 복합층(110)의 길이(longitudinal) 방향에 대하여 수직(

)이 된다.In this case, the magnetization direction of the first magnet member 150 and the second magnet member 160 (

) is perpendicular to the longitudinal direction of the composite layer 110 (

) becomes

2B, in the ferroelectric-ferromagnetic composite laminate structure 100b, the first magnet member 150 is disposed above the second magnetostrictive layer 140, and the second magnet member 160 is It may be disposed below the first magnetostrictive layer 120 .

In the first magnet member 150 , a first N pole 151 and a first S pole 152 may be sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer 140 . In the second magnet member 160 , a second S pole 162 and a second N pole 161 may be sequentially disposed in a direction perpendicular to the lower surface of the first magnetostrictive layer 120 .

In addition, the arrangement order of the first N pole 151 and the first S pole 152 may be changed, and the arrangement order of the second N pole 161 and the second S pole 162 may be changed with each other. In the first magnet member 150 , a first S pole 152 and a first N pole 151 may be sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer 140 . In the second magnet member 160 , a second N pole 161 and a second S pole 162 may be sequentially disposed in a direction perpendicular to the lower surface of the first magnetostrictive layer 120 .

)이 복합층(110)의 길이 방향에 대하여 수직(

)이 된다.In this case, the magnetization direction of the first magnet member 150 and the second magnet member 160 (

) is perpendicular to the longitudinal direction of the composite layer 110 (

) becomes

Referring to FIG. 2C , in the ferroelectric-ferromagnetic composite laminate structure 100c , the first magnet member 150 and the second magnet member 160 may be disposed on the upper side of the second magnetostrictive layer 140 . have.

In the first magnet member 150 , a first S pole 152 and a first N pole 151 may be sequentially disposed in a horizontal direction with respect to the upper surface of the second magnetostrictive layer 140 . In the second magnet member 160 , a second S pole 162 and a second N pole 161 may be sequentially disposed in a horizontal direction with respect to the upper surface of the second magnetostrictive layer 140 . In this case, the first S pole 152 , the first N pole 151 , the second S pole 162 , and the second N pole 161 may be in the order of the horizontal direction.

In addition, the arrangement order of the first N pole 151 and the first S pole 152 may be changed, and the arrangement order of the second N pole 161 and the second S pole 162 may be changed with each other. In the first magnet member 150 , a first N pole 151 and a first S pole 152 may be sequentially disposed in a horizontal direction with respect to the upper surface of the second magnetostrictive layer 140 . In the second magnet member 160 , a second N pole 161 and a second S pole 162 may be sequentially disposed in a horizontal direction with respect to the upper surface of the second magnetostrictive layer 140 . In this case, the first N pole 151 , the first S pole 152 , the second N pole 161 , and the second S pole 162 may be in the order of the horizontal direction.

)이 복합층(110)의 길이 방향에 대하여 수평(

)이 된다.In this case, the magnetization direction of the first magnet member 150 and the second magnet member 160 (

) is horizontal (

) becomes

Referring to (d) of FIG. 2, in the ferroelectric-ferromagnetic composite laminate structure 100d, the first magnet member 150 is disposed on the upper side of the second magnetostrictive layer 140, and the second magnet member 160 is It may be disposed below the first magnetostrictive layer 120 .

In the first magnet member 150 , a first S pole 152 and a first N pole 151 may be sequentially disposed in a horizontal direction with respect to the upper surface of the second magnetostrictive layer 140 . In the second magnet member 160 , a second S pole 162 and a second N pole 161 may be sequentially disposed in a horizontal direction with respect to the lower surface of the first magnetostrictive layer 120 .

In addition, the arrangement order of the first N pole 151 and the first S pole 152 may be changed, and the arrangement order of the second N pole 161 and the second S pole 162 may be changed with each other. In the first magnet member 150 , a first N pole 151 and a first S pole 152 may be sequentially disposed in a horizontal direction with respect to the upper surface of the second magnetostrictive layer 140 . In the second magnet member 160 , a second N pole 161 and a second S pole 162 may be sequentially disposed in a horizontal direction with respect to the lower surface of the first magnetostrictive layer 120 . In this case, the first N pole 151 , the first S pole 152 , the second N pole 161 , and the second S pole 162 may be in the order of the horizontal direction.

)이 복합층(110)의 길이 방향에 대하여 수평(

)이 된다.In this case, the magnetization direction of the first magnet member 150 and the second magnet member 160 (

) is horizontal (

) becomes

The arrangement of the first magnet member 150 and the second magnet member 160 shown in FIG. 2 generates a linear magnetic field (H _PA ) in the first magnetostrictive layer 120 and the second magnetostrictive layer 140 by attractive magnetic force. can be formed.

For reference, the arrangement for forming the repulsive magnetic force of the first magnet member 150 and the second magnet member 160 was found to be inefficient in the self-bias magnetoelectric reaction (that is, the movement of the λ curve with respect to H _DC ) and was omitted. , the technical idea of the present invention also includes an arrangement for forming such a repulsive magnetic force.

3 is a schematic diagram illustrating a ferroelectric-ferromagnetic composite laminate structure 200 according to an embodiment of the present invention.

Referring to FIG. 3 , the ferroelectric-ferromagnetic composite laminate structure 200 includes a first magnetostrictive layer 220 , a piezoelectric layer 230 positioned on the first magnetostrictive layer 220 , and a first magnetostrictive layer positioned on the piezoelectric layer 230 . a composite layer 210 including two magnetostrictive layers 240 ; a first magnet member 250 spaced apart from one side of the composite layer 210; a first rotating member 280 functioning as a rotating shaft for rotating the first magnet member 250; and a second magnet member 260 spaced apart from the other side of the composite layer 210 .

In addition, the ferroelectric-ferromagnetic composite laminate structure 200 may further include a second rotating member 290 serving as a rotation shaft for rotating the second magnet member 260 .

In addition, the ferroelectric-ferromagnetic composite laminate structure 200 may further include a fixing member 270 located in the center of the composite layer 210 to fix the composite layer 210 .

The first magnet member 250 may include a first N pole 251 and a first S pole 252 . The second magnet member 260 may include a second N pole 261 and a second S pole 262 .

The first rotating member 280 may function as a rotating shaft for rotating the first magnet member 250 . The second rotating member 290 may function as a rotating shaft for rotating the second magnet member 260 . The first rotating member 280 and the second rotating member 290 may include various rotatable elements, and may be connected to or separated from the composite layer 210 .

Since the magnetic pole directions of the first magnet member 250 and the second magnet member 260 can be simply changed by the first rotating member 280 and the second rotating member 290, the self-bias magnetoelectric voltage coefficient or The self-biased magnetoelectric voltage output can be easily adjusted. Accordingly, the ferroelectric-ferromagnetic composite laminate structure according to the technical spirit of the present invention can facilitate adjustment of a self-biased magnetoelectric device.

Experimental example

Hereinafter, preferred experimental examples are presented to help the understanding of the present invention. However, the following experimental examples are only for helping understanding of the present invention, and the present invention is not limited by the following experimental examples.

Fabrication of ferroelectric-ferromagnetic composite laminate structures

A composite layer 110 including the first magnetostrictive layer 120 , the piezoelectric layer 130 , and the second magnetostrictive layer 140 was formed.

The first magnetostrictive layer 120 and the second magnetostrictive layer 140 include different materials. The lower first magnetostrictive layer 120 was composed of nickel (99+%, Nilaco Corp.) and had a thickness of 160 μm. The second magnetostrictive layer 140 positioned on the upper portion was made of FeSiB-based alloy, that is, Metglass (2605SA1, Metglas Inc.), and had a thickness of 150 μm.

The piezoelectric layer 130 was composed of Pb(Zr,Ti)O ₃ , that is, a PZT-based 31-mode piezoelectric ceramic (PSI-5H4E, Piezo systems Inc.), and had a thickness of 250 μm. The piezoelectric layer 130 was polarized in the thickness direction.

A second magnetostrictive layer 140 made of met glass was attached to the upper surface of the piezoelectric layer 130 , and a first magnetostrictive layer 120 made of nickel was attached to the lower surface of the piezoelectric layer 130 . This attachment was made using an epoxy adhesive (DP460, 3M), followed by curing at 80° C. to complete the composite layer 110 . The dimensions of the composite layer 110 were 60 mm in length and 5 mm in width.

Next, the first magnet member 150 and the second magnet member 160 were attached to both ends of the composite layer 110 . The attachment was made by curing at 80° C. with an epoxy adhesive. The first magnet member 150 and the second magnet member 160 were configured to include Nd magnets (6 mm x 4 mm x 3 mm), respectively. The arrangement of the first magnet member 150 and the second magnet member 160 is as shown in FIG. 2 . Accordingly, the ferroelectric-ferromagnetic composite laminate structure 100 was completed.

As a comparative example, the composite layer 110 in which the first magnet member 150 and the second magnet member 160 are not disposed was separately formed.

Characteristics analysis method of ferroelectric-ferromagnetic composite laminate structure

The phase angle spectrum of the ferroelectric-ferromagnetic composite laminate was measured using an impedance analyzer (IM3570, Hioki).

The operation of the ferroelectric-ferromagnetic composite laminate structure was observed using a scanning laser vibrometer (Polytec, PSV 500).

In order to analyze the magnetoelectric reaction of the ferroelectric-ferromagnetic composite laminate structure, the apparatus of FIG. 4 was used.

4 is a photograph showing a measuring device for measuring magnetoelectric voltage output of a ferroelectric-ferromagnetic composite laminate structure according to an embodiment of the present invention.

Referring to FIG. 4 , the ferroelectric-ferromagnetic composite laminate structure is positioned at the center of a Helmholtz coil located at the center of an electromagnet, and is fixed using a fixing member. Then, the voltage induced in the ferroelectric-ferromagnetic composite laminate structure by the magnetic force of the electromagnet was observed using a lock-in amplifier (SR860, Stanford Research system).

Results and analysis

In the following description, Example 1 corresponds to FIG. 2(a), Example 2 corresponds to FIG. 2(b), Example 3 corresponds to FIG. 2(c), and Example 4 corresponds to FIG. 2(c). It corresponds to Fig. 2 (d).

5 is a graph showing a phase angle spectrum of a ferroelectric-ferromagnetic composite laminate structure according to an embodiment of the present invention.

Referring to FIG. 5 , in the case of the comparative example in which the magnet member is not disposed, the composite layer of the met glass layer/PZT layer/nickel layer exhibits a bending resonance peak at a frequency of about 483 Hz. However, in all the examples in which the magnet member is disposed with the composite layer of the met glass layer/PZT layer/nickel layer, the ferroelectric-ferromagnetic composite laminate structure exhibits a bending resonance peak at a frequency in the range of about 255 to 263 Hz.

In the composite layer of the metglass layer/PZT layer/nickel layer, the piezomagnetic coefficient of the metglass is +q because it has a positive sign, and the piezoelectricity coefficient of the nickel is -q because it has a negative sign. When the ferroelectric-ferromagnetic composite laminate structure is exposed to an alternating magnetic field (H _AC ), a bending operation of the composite layer may be expressed. In the case of the embodiment, since the bending resonance frequency is low, it may be effective to achieve a low frequency bending resonance.

6 is a photograph showing the bending behavior of a ferroelectric-ferromagnetic composite laminate structure according to an embodiment of the present invention.

Referring to FIG. 6 , the ferroelectric-ferromagnetic composite laminate of Example 1 exhibits bending behavior at 262 Hz and 2 V.

7 is a graph showing a magnetoelectric voltage coefficient with respect to a DC bias magnetic field of a comparative example for comparison with a ferroelectric-ferromagnetic composite laminate structure according to an embodiment of the present invention.

Referring to FIG. 7 , the magnetoelectric voltage coefficient (α _ME ) relationship with the DC bias magnetic field (H _DC ) of the comparative example in which the magnet member is not disposed is shown. The results were obtained at a frequency of 483 Hz and H _AC = 1 Oe at which the bending resonance peak appeared. The magnetoelectric voltage coefficient (α _ME ) is calculated by α _ME = E _AC /H _AC , H _AC is an alternating magnetic field, and E _AC is an output electric field.

In the case of the comparative example, a symmetrical pattern is exhibited at the origin based on H _DC = 0 without the DC bias magnetic field. That is, when the direction of the DC bias magnetic field is reversed and the sign is different, but the magnitude of the absolute value is the same, the absolute value of the magnetoelectric voltage coefficient is almost the same.

8 is a graph showing a magnetoelectric voltage coefficient with respect to a DC bias magnetic field of a ferroelectric-ferromagnetic composite laminate structure according to Example 1 of the present invention.

(a) of FIG. 8 shows the relationship between the magnetoelectric voltage coefficient with respect to the DC bias magnetic field, and (b) shows the integral value. Also, FIG. 8 is a result of a _{ferroelectric} -ferromagnetic composite laminate structure having the structure of Example 1 of FIG. However, in case ①, the composite layer is composed of a metglass layer/PZT layer/nickel layer, and magnet members are attached to the upper side of the metglass layer, in case ②, the composite layer is a nickel layer/PZT layer/metglass It is composed of layers, and the magnet members are attached to the upper side of the nickel layer.

Referring to FIG. 8 , unlike the comparative example of FIG. 7 , the relationship between the magneto-electrical voltage coefficient (α _ME ) with respect to the DC bias magnetic field (H _DC ) has significantly reduced symmetry in both cases. In particular, the magnetoelectric voltage coefficient (α _ME ) was large at H _DC = 0, and this will be referred to as the self-bias magnetoelectric voltage coefficient (α _SME ).

In FIG. 8 (a), the amount of magnetic field movement (ΔH) from the origin to the point where the DC bias magnetic field becomes 0 along the DC bias magnetic field (H _DC ) axis indicated by the x-axis is the linear magnetic field (H _PA ) in the magnetostrictive layer. It can be determined by the distribution. The magnetic field shift amount ΔH refers to a direct current bias magnetic field H _DC that causes the effective magnetization to be zero in the magnetostrictive layer.

In FIG. 8B , since the magnetoelectric voltage coefficient α _ME is directly proportional to the piezoelectric coefficient q , the cumulative value of the magnetoelectric voltage coefficient α _ME over the DC bias magnetic field H _DC . is proportional to the effective magnetostrictive strain (λ _eff ) of the magnetostrictive layer.

In case ①, the magnetic field shift amount (ΔH) was 20.42 Oe, and the self-bias magnetoelectric voltage coefficient (α _SME ) was 52.35 Vcm ^-1 Oe ^-1 . In case ②, the magnetic field shift amount (ΔH) was 13.51 Oe, and the self-bias magnetoelectric voltage coefficient (α _SME ) was 23.39 Vcm ^-1 Oe ^-1 . In the above case, the values of ② appeared to be about half of the values of ①.

In case ①, the absolute value of +α _MAX at point a where the magnetoelectric voltage coefficient (α _ME ) is maximally increased to a positive value is negative value of -α _MAX at the point b maximally decreased. was larger than the absolute value. On the other hand, in case ②, the absolute value of +α _MAX at the point c where the magnetoelectric voltage coefficient (α _ME ) is maximally increased to a positive value is -α _MAX at the point d where the absolute value is decreased to a negative value. was smaller than the absolute value of

9 is a graph showing the magnetoelectric voltage coefficient with respect to the DC bias magnetic field of the ferroelectric-ferromagnetic composite laminate structure according to Example 2 of the present invention.

Referring to FIG. 9 , the relationship between the magnetoelectric voltage coefficient and the DC bias magnetic field of the ferroelectric-ferromagnetic composite laminate structure having the structure of Example 2 of FIG. 2B is shown. The composite layer was composed of a met glass layer/PZT layer/nickel layer, and magnet members were attached to the upper and lower sides of the composite layer, respectively. The above results were obtained at a frequency of 263 Hz and H _AC = 1 Oe at which the bending resonance peak appeared.

In Example 2, there was little difference between the absolute value of +α _MAX and the absolute value of -α _MAX differently from the result of FIG. 8 . The fact that the symmetry shown in FIG. 7 is significantly reduced is consistent with the result of FIG. 8 . In Example 2, the magnetic field shift amount (ΔH) was 20.97 Oe, and the self-bias magnetoelectric voltage coefficient (α _SME ) was 28.25 Vcm ^-1 Oe ^-1 .

10 is a schematic diagram illustrating a magnetic field distribution formed in a ferroelectric-ferromagnetic composite laminate structure according to Examples 1 and 2 of the present invention.

10, (a) corresponds to Example 1, (b) corresponds to Example 2.

) 인가하면, 즉 도면에서 좌측 방향으로 인가하면서, 자기전기 전압 계수(α_ME)의 변화를 분석할 수 있다. 즉, 상기 역방향은 도 8의 (a)에서 상기 경우 ①은 a 점에서 b 점으로의 방향이고, 상기 경우 ②는 c 점에서 d 점으로의 방향이다.Referring to (a) of FIG. 10 , when the DC bias magnetic field H _DC is 0, the linear magnetic field H _PA is concentrated in the magnetostrictive layer located on the upper side, that is, the second magnetostrictive layer, and the magnetostriction layer located on the lower side. , that is, relatively weak in the first magnetostrictive layer. In addition, the external magnetic field (H _out ) formed on the composite layer between the two magnet members is formed at a significant level that cannot be ignored. At this time, the direct current bias magnetic field (H _DC ) in the reverse direction (

), that is, while applying in the left direction in the drawing, the change in the magnetoelectric voltage coefficient (α _ME ) can be analyzed. That is, the reverse direction is the direction from the point a to the point b in the case ① in FIG.

의 값이 점진적으로 증가되면, 상기 자왜층의 유효 자왜 변형률(λ_eff) 곡선의 기울기는 점진적으로 감소되고, 도 8의 (b)에 나타난 점 f에서 0이 될 수 있다. 상기 점 f에서, 교류 자기장(H_AC)이 1 Oe 인 경우, 메트글라스층과 니켈층의 유효 변형율이 0이 된다. 즉, 상기 점 f에서 상기 자왜층들의 국부 자화 쌍극자들의 방향이 무작위가 된다. In case ①, the +α _MAX appears at the point a where the DC bias magnetic field (H _DC ) is close to zero, and the slope of the effective magnetostrictive strain (λ _eff ) curve of the magnetostrictive layer is determined by the linear magnetic field (H _PA ) becomes the maximum By the magnetic field movement amount (ΔH)

When the value of is gradually increased, the slope of the effective magnetostrictive strain (λ _eff ) curve of the magnetostrictive layer is gradually decreased, and may become 0 at the point f shown in FIG. 8B . At the point f, when the alternating magnetic field (H _AC ) is 1 Oe, the effective strains of the metglass layer and the nickel layer become zero. That is, the directions of the localized dipoles of the magnetostrictive layers at the point f become random.

의 방향으로 정렬되고, 상기 유효 자왜 변형률(λ_eff) 곡선의 두번째로 최대인 기울기가 도 8의 (b)에 나타난 g 점에서 나타나고, 상기 g 점은 상기 b 점의 -α_MAX 에 상응한다. 여기에서, 상기 a 점에서 상기 b 점으로 진행되는 동안, 외부 자기장(H_out)의 방향과

의 방향이 일치한다.Then, the locally magnetized dipoles are demagnetized as the strength of the magnetic field increases.

Aligned in the direction of , the second maximum slope of the effective magnetostrictive strain (λ _eff ) curve appears at point g shown in FIG. 8B , and the point g corresponds to -α _MAX of the point b. Here, while proceeding from the point a to the point b, the direction of the external magnetic field (H _out ) and

direction coincides with

Subsequently, a significant amount of attractive force by an external magnetic field (H _out ) provides compressive stress to the second magnetostrictive layer, which is the metglass, located on the upper side, and provides tensile stress to the nickel layer, which is the first magnetostrictive layer located on the lower side. do. Since these stresses act in opposite directions to the piezoelectric properties (+q) of the metglass layer and the piezomagnetic properties (-q) of the nickel layer, -α _MAX becomes smaller than the +α _MAX .

의 양은 상기 경우 1에 비하여 작다. 이는 상기 메트글라스층과 상기 니켈층 사이의 직류 바이어스 자기장(H_DC)에 대한 자왜 변형률(λ)의 차이에 기인할 수 있다.On the other hand, in the case ②, the +α _MAX appears at the c point, which means that the effective magnetostrictive strain (λ _eff ) curve becomes the maximum slope at the h point shown in (b) of FIG. 8, and the line magnetic field (H _PA ) It can be seen that this is a slightly larger number than the amount required to obtain the maximum self-bias magnetoelectric voltage coefficient (α _SME ). In addition, in the magnetic field shift amount (ΔH), it is necessary to make the slope of the effective magnetostrictive strain (λ _eff ) curve (point i) to zero.

The amount of is smaller than that of 1 in the above case. This may be due to a difference in magnetostrictive strain (λ) with respect to a DC bias magnetic field (H _DC ) between the metglass layer and the nickel layer.

In the first embodiment, since the magnetic field (H _PA ) is concentrated on the magnetostrictive layer to which the magnet member is attached, the magnetostrictive layer located on the upper side, that is, the second magnetostrictive layer, may lead the initial magnetoelectric reaction. In the case ①, the concentrated magnetic field (H _PA ) may be suitable to obtain the largest gradient of the magnetostrictive strain (λ) with respect to the DC bias magnetic field (H _DC ) of the metglass layer. Accordingly, the self-bias magnetoelectric voltage coefficient α _SME is approximately equal to the +α _MAX .

On the other hand, in the case of the nickel layer, the maximum q value and the DC bias magnetic field (H _DC ) required for the maximum q value are lower than those of the metglass layer. Accordingly, in case ②, the magnetic field movement amount ΔH is smaller than in case ①, and the self-bias magnetoelectric voltage coefficient α _SME is smaller than the +α _MAX .

The difference between the +α _MAX in the case ① and the case ② indicates that in Example 1, the second magnetostrictive layer located on the upper side leads the magnetoelectric reaction.

), 외부 자기장(H_out)에 의하여 상측에 위치한 제2 자왜층인 니켈층에는 압축 응력이 인가되고, 하측에 위치한 제1 자왜층인 메트글라스층에는 인장 응력이 인가된다. 이러한 응력들은 상기 메트글라스층의 압자기 특성(+q)과 상기 니켈층의 압자기 특성(-q)에 의한 상기 적층 구조체의 굽힘 거동과 부합된다. 따라서, 점 j에서 유효 자왜 변형률(λ_eff) 곡선의 기울기가 가장 크게 된다.In case ②, since the absolute value of -α _MAX (point d) is greater than the absolute value of +α _MAX (point c), it can be seen that an external magnetic field H _out exists. In case ②, when reverse bias is applied (

) and an external magnetic field (H _out ), compressive stress is applied to the nickel layer, which is the second magnetostrictive layer located on the upper side, and tensile stress is applied to the first magnetostrictive layer, which is the metglass layer, located on the lower side. These stresses coincide with the bending behavior of the laminated structure due to the magnetostatic characteristics (+q) of the metglass layer and the magnetostatic characteristics (-q) of the nickel layer. Therefore, the slope of the effective magnetostrictive strain (λ _eff ) curve becomes the largest at point j.

Referring to (b) of Figure 10, Example 2 shows a different magnetic field distribution from Example 1. The linear magnetic field (H _PA ) is uniformly distributed in the second magnetostrictive layer located on the upper side and the first magnetostrictive layer located on the lower side, and the influence of the external magnetic field (H _out ) between the two magnet members is negligible. Accordingly, as shown in FIG. 9 , the absolute value of +α _MAX and the absolute value of -α _MAX are almost the same, which is analyzed because stresses causing bending behavior do not exist.

In addition, the +α _MAX and self-bias magnetoelectric voltage coefficient (α _SME ) of the second embodiment are small compared to ① in the first embodiment, but larger than the ② in the first embodiment. The reason is analyzed that in Example 2, the metglass layer and the nickel layer simultaneously contribute to the initial magnetoelectric reaction.

From these results, it can be seen that when the pre-magnetic field (H _PA ) is concentrated on the metglass layer, it is effective to implement a high self-bias magnetoelectric voltage coefficient (α _SME ). In particular, it is effective when the metglass layer is a second magnetostrictive layer positioned on the upper side, and two magnet members are disposed on the second magnetostrictive layer.

11 is a graph showing magnetoelectric voltage coefficients with respect to a DC bias magnetic field of a ferroelectric-ferromagnetic composite laminate structure according to Examples 3 and 4 of the present invention.

11, the result of the ferroelectric-ferromagnetic composite laminate structure having the structures of Example 3 of FIG. 2(c) and Example 4 of FIG. Acquired at 255 Hz and H _AC = 1 Oe. In both cases, the composite layer is composed of a met glass layer/PZT layer/nickel layer.

First, unlike the comparative example of FIG. 7 , the relationship between the magneto-electrical voltage coefficient (α _ME ) with respect to the DC bias magnetic field (H _DC ) has significantly reduced symmetry in both cases.

In Example 3, it can be seen that the magnetic field (H _PA ) is concentrated in the upper second magnetostrictive layer formed of the met glass layer. Accordingly, the +α _MAX is 18.04 Vcm ^-1 Oe ^-1 , which is very small compared to the case ① of Example 1. The magnetic field shift amount (ΔH) was 35.63 Oe, which was 70% larger than that of the case ① of Example 1. The self-bias magnetoelectric voltage coefficient (α _SME ) was 14.11 Vcm ^-1 Oe ^-1 , and was relatively small compared to the case ① of Example 1.

In Example 4, the +α _MAX and the self-bias magnetoelectric voltage coefficient (α _SME ) were slightly larger than those of Example 3.

In Examples 3 and 4, since the absolute value of +α _MAX is almost similar to the absolute value of -α _MAX , it is analyzed that there is little influence of the external magnetic field H _out .

12 is a schematic diagram showing a magnetic field distribution formed in a ferroelectric-ferromagnetic composite laminate structure according to Examples 3 and 4 of the present invention.

12 , Example 3 shows a magnetic field _distribution similar to that of Example 1 of FIG. , is relatively weak to the magnetostrictive layer located below, that is, the first magnetostrictive layer.

Example 4 shows a magnetic field _distribution similar to that of Example 2 of FIG. have. However, the magnetic field shift amount ΔH and the self-bias magnetoelectric voltage coefficient α _SME of Example 4 are very different from those of Example 2.

경우에 비하여, 실시예1과 실시예2에 해당되는

경우가 더 크게 나타나는 것으로 분석된다.The self-bias magnetoelectric voltage coefficient (α _SME ) of Examples 3 and 4 was smaller than that of Examples 1 and 2. Therefore, when the direct current bias magnetic field (H _DC ) is 0, the change (Δλ) of the magnetostrictive strain (λ) of the magnetostrictive layer under the alternating magnetic field (H _AC ) corresponds to Examples 3 and 4

In contrast to the case, in Examples 1 and 2,

cases are considered to be larger.

13 is a schematic diagram illustrating a magnetic field and magnetization (M) behavior formed in a magnetostrictive layer in a ferroelectric-ferromagnetic composite laminate structure according to Examples 1 and 3 of the present invention.

가 복합층의 길이 방향에 대하여 수직인 경우이고, 이를

로 표시한다. 도 13의 (b)는

가 복합층의 길이 방향에 대하여 수평인 경우이고,

로 표시한다.13 (a) is

is perpendicular to the longitudinal direction of the composite layer, and

indicated as 13 (b) is

When is horizontal to the longitudinal direction of the composite layer,

indicated as

를 나타내며, 상기

의 크기가 상기 황색 화살표의 길이로 나타나있다. 직류 바이어스 자기장(H_DC)은 0이다. In FIG. 13 , white lines indicate the magnetic field (H _PA ) of the second magnetostrictive layer located on the upper side, and the strength of the magnetic field is indicated by the size of the head of the white arrow. Yellow arrows indicate the second magnetostrictive layer.

represents, and

The size is indicated by the length of the yellow arrow. The DC bias magnetic field (H _DC ) is zero.

), 또는, 국부 자구에서의 자화 쌍극자 모멘트를 정렬시킬 수 있다. 실시예1인 상기

과 실시예3인 상기

을 비교하면, 상기 선자기장(H_PA)의 분포와 상기

의 분포가 다름을 알 수 있다. 상기 선자기장(H_PA) 분포에 기반하여, 상측에 위치한 자왜층에서 두 개의 다른 자화 영역들, 즉 영역 I 과 영역 II로서 구분될 수 있다. 상기 영역 I에서는 모든 자구가 길이 방향에 평행하게 배치되는 반면, 상기 영역 II에서는 자구의 방향이 상기 길이 방향에 평행하지 않게 배치된다.13, the linear magnetic field (H _PA ) formed by the magnet members is localized in the magnetostrictive layer (

), or, it is possible to align the magnetizing dipole moment in the local magnetic domain. Example 1 above

and Example 3 above

By comparing the distribution of the magnetic field (H _PA ) and the

It can be seen that the distribution of Based on the linear magnetic field (H _PA ) distribution, the magnetostrictive layer located on the upper side may be divided into two different magnetization regions, that is, region I and region II. In the region I, all magnetic domains are arranged parallel to the longitudinal direction, whereas in the region II, the directions of the magnetic domains are non-parallel to the longitudinal direction.

와 상기

에서, 상기 선자기장(H_PA)의 강도는 상기 자석부재에 인접한

가 포화될 정도로 크게 되고, 상기 적층 구조체의 중간에서는 가장 작게 된다. 따라서, 상기

크기는 상기 자왜층을 가로질러 점진적으로 변화됨을 알 수 있다.remind

and above

In, the strength of the magnetic field (H _PA ) adjacent to the magnet member

becomes large enough to be saturated, and becomes smallest in the middle of the stacked structure. Therefore, the

It can be seen that the size is gradually changed across the magnetostrictive layer.

에서, 상기 영역 I은 상기 길이 방향에 평행하고 상대적으로 작은

크기를 가지는 자구들로 구성된다. 반면 상기 영역 II는 상기 길이 방향에 대하여 다양한 각도들 (θ_i)을 가지는 자구들로 구성되고, 상기 자구들은 거의 포화된

크기를 가진다.The above example 1 of FIG. 13(a)

In , the region I is parallel to the longitudinal direction and has a relatively small

It is composed of magnetic domains of size. On the other hand, the region II is composed of magnetic domains having various angles (θ _i ) with respect to the longitudinal direction, and the magnetic domains are almost saturated.

have a size

에서, 실시예1인 상기

의 영역 I에 비하여, 상기 영역 I이 더 넓게 되고, 자구들은 실시예1과는 다르게 작은 값에서 포화값까지의 다양한

크기를 가짐을 알 수 있다. 상기

는 실시예1인 상기

의 영역 II에 비하여, 영역 II가 매우 좁으며, 90도 및 180도의 θ_i 을 가지는 자구들이 상기 영역 II에 주로 형성됨을 알 수 있다.Example 3 of Figure 13 (b)

In Example 1, the above

Compared to the region I of

It can be seen that the size has remind

is the above example 1

It can be seen that region II is very narrow compared to region II of , and magnetic domains having θ _i of 90 degrees and 180 degrees are mainly formed in region II.

의 재분포에 의한 자왜 변형률의 변화(Δλ)을 분석하기로 한다.In the following, under the small fluctuations (δH _DC : amplitude of the alternating magnetic field (H _AC )) in the region I and the DC bias magnetic field (H _DC ) in the region and II,

We will analyze the change in magnetostrictive strain (Δλ) due to the redistribution of .

14 is a schematic diagram illustrating a change in magnetization of a magnetostrictive layer when a minute DC bias magnetic field is applied in the ferroelectric-ferromagnetic composite laminate structure of the present invention.

의 크기 변화에 의한 자왜 변화의 기여, 즉 Δλ(M), 및

의 회전에 의한 자왜 변형률의 변화의 기여, 즉 Δλ(θ), 로 분리할 수 있다.Referring to FIG. 14 , when the DC bias magnetic field is not 0, the change in the total magnetostrictive strain (Δλ) is

The contribution of the magnetostrictive change by the change in magnitude of , i.e. Δλ(M), and

The contribution of the change in magnetostrictive strain due to rotation of , that is, Δλ(θ), can be divided into .

The Δλ(M) may be determined by the following equation.

Here, λ _S is the saturated magnetostrictive strain, and M _s is the saturated magnetization.

The Δλ(θ) may be determined by the following equation.

Here, <cos ² θ _i > represents the average value of cos ² θ _i for all orientations in the initial state (θ _i ), and <cos ² θ _f > is the average value of cos 2 θ i for all orientations in the final state (θ _f ). It represents the average value of cos ² θ _f for

경우와 상기

경우가 유사하게 취급될 수 있다. 그 이유는 상기 영역 I에서는 포화되지 않은

가 Δλ(M)에 기여하기 때문이다.In the region I, since θ _i = θ _f , Δλ(θ) is negligible, and Δλ(M) is

case and above

The case can be treated similarly. The reason is that the region I is not saturated

This is because Δλ(M) contributes to Δλ(M).

경우의 영역 II에서의 Δλ(θ)는 무시할 수 없고, 전체 자왜 변형률의 변화(Δλ)에 효과적으로 기여할 수 있다. 상기

경우의 영역 II에서의 Δλ(θ)가 0 이 아니지만, θ_i = 90도의 자구들을 가지는 좁은 영역에 의하여 전체 자왜 변형률의 변화(Δλ)에 대한 기여가 매우 작음을 알 수 있다.However, said

Δλ(θ) in the region II of the case cannot be neglected, and can effectively contribute to the change (Δλ) of the total magnetostrictive strain. remind

Although Δλ(θ) in the region II of the case is not 0, it can be seen that the contribution to the change (Δλ) of the total magnetostrictive strain is very small due to the narrow region having magnetic domains of θ _i = 90 degrees.

경우의 영역 II에서의 θ_i = 180도의 자구들은 전체 자왜 변형률의 변화(Δλ)에 거의 기여하지 않는 것으로 분석되며, 그 이유는 상기

경우에서는 Δλ(M)의 부호가 반대이기 때문이다.remind

It is analyzed that the magnetic domains of θ _i = 180 degrees in the region II of the case hardly contribute to the change (Δλ) of the total magnetostrictive strain, because the

This is because the sign of Δλ(M) is opposite in this case.

15 is a graph showing magnetoelectric voltage coefficients with respect to a DC bias magnetic field under an alternating magnetic field of a ferroelectric-ferromagnetic composite laminate structure according to Examples 1 and 3 of the present invention.

경우에 비하여 상기

경우에서, 자왜 변형률의 변화(Δλ)가 더 크며, 셀프 바이어스 자기전기 전압 계수(α_SME)가 더 크게 나타난다.Referring to FIG. 15 , it is a measurement result by applying an alternating magnetic field of 1 Oe at each bending resonant frequency. Under the same δH _DC , or alternating magnetic field (H _AC ), the

compared to the case

In this case, the change in magnetostrictive strain (Δλ) is larger, and the self-biased magnetoelectric voltage coefficient (α _SME ) is larger.

경우에 비하여 상기

경우가 훨씬 더 작게 나타났다. 상기

경우에서 상기 직류 바이어스 자기장(H_DC)에 평행한 선자기장(H_PA)이 더 크게 나타났고, 이에 따라 상기 자기장 이동량(ΔH)이 상기

경우에서 더 크게 나타났다.In the region I, the magnitude of the magnetization parallel to the longitudinal direction of the stacked structure, that is, the direction parallel to the direct current bias magnetic field (H _DC ) is the

compared to the case

cases were much smaller. remind

In this case, the linear magnetic field (H _PA ) parallel to the DC bias magnetic field (H _DC ) was larger, and accordingly, the magnetic field movement amount (ΔH) was

cases were larger.

conclusion

A strong self-bias magnetoelectric response was experimentally demonstrated for a ferroelectric-ferromagnetic composite laminate structure having a composite layer of a mat glass layer/PZT layer/Ni layer on which a pair of magnet members are disposed. As a result of analyzing the magnetoelectric properties of the ferroelectric-ferromagnetic composite laminate structure to which two permanent magnets are attached in four arrangements, the magnet member is disposed on a mat glass layer (high +q material), and their magnetization direction is The highest self-bias magnetoelectric effect was observed in the case perpendicular to the surface of the metglass layer. Analyzing the cause of the observed magnetoelectric reaction, it is analyzed that non-parallel ferromagnetic dipoles effectively contribute to the total magnetostriction and do not affect the amount of magnetic field shift (ΔH). The ferroelectric-ferromagnetic composite layered structure in which the magnetic field was formed exhibited a strong self-biased magnetoelectric voltage coefficient ranging from 14.11 Vcm ^-1 Oe ^-1 to 52.35 Vcm ^-1 Oe ^-1 at about 260 Hz under a 1 Oe alternating magnetic field. This high self-bias magneto-electrical voltage coefficient can be applied to precise magnetic field sensors, magnetic energy harvesters, and electric and magnetic field-controlled self-biased magnetoelectric devices.

The technical spirit of the present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is the technical spirit of the present invention that various substitutions, modifications and changes are possible without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in the art to which this belongs.

100, 100a, 100b, 100c, 100d: ferroelectric-ferromagnetic composite laminate structure,
110: composite layer, 120: first magnetostrictive layer;
130: piezoelectric layer, 140: second magnetostrictive layer,
150: a first magnet member, 151: a first N pole,
152: a first S pole, 160: a second magnet member,
161: a second N pole, 162: a second S pole,
170: fixing member;
200: ferroelectric-ferromagnetic composite laminate structure,
210: composite layer, 220: first magnetostrictive layer;
230: a piezoelectric layer, 240: a second magnetostrictive layer;
250: a first magnet member, 251: a first N pole,
252: a first S pole, 260: a second magnet member,
261: a second N pole, 262: a second S pole,
270: a fixing member, 280: a first rotating member,
290: a second rotating member;

Claims (17)

a composite layer including a first magnetostrictive layer, a piezoelectric layer positioned on the first magnetostrictive layer, and a second magnetostrictive layer positioned on the piezoelectric layer;
a first magnet member disposed on one end of the composite layer; and
Containing; a second magnet member disposed on the other end of the composite layer;
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
The first magnet member and the second magnet member are disposed above the second magnetostrictive layer,
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
The first magnet member is disposed above the second magnetostrictive layer,
The second magnet member is disposed below the first magnetostrictive layer,
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
In the first magnet member, a first N pole and a first S pole are sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer,
In the second magnet member, a second S pole and a second N pole are sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer,
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
In the first magnet member, a first S pole and a first N pole are sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer,
In the second magnet member, a second N pole and a second S pole are sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer,
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
In the first magnet member, a first N pole and a first S pole are sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer,
In the second magnet member, a second S pole and a second N pole are sequentially arranged in a direction perpendicular to the lower surface of the first magnetostrictive layer,
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
In the first magnet member, a first S pole and a first N pole are sequentially disposed in a direction perpendicular to the upper surface of the second magnetostrictive layer,
In the second magnet member, a second N pole and a second S pole are sequentially disposed in a direction perpendicular to the lower surface of the first magnetostrictive layer,
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
In the first magnet member, a first S pole and a first N pole are sequentially arranged in a horizontal direction with respect to the upper surface of the second magnetostrictive layer,
In the second magnet member, a second S pole and a second N pole are sequentially arranged in a horizontal direction with respect to the upper surface of the second magnetostrictive layer,
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
In the first magnet member, a first S pole and a first N pole are sequentially arranged in a horizontal direction with respect to the upper surface of the second magnetostrictive layer,
In the second magnet member, a second S pole and a second N pole are sequentially arranged in a horizontal direction with respect to the lower surface of the first magnetostrictive layer,
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
Further comprising; a fixing member located in the center of the composite layer to fix the composite layer;
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
The first magnetostrictive layer has a negative piezomagnetic coefficient,
wherein the second magnetostrictive layer has a positive piezomagnetic coefficient;
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
the first magnetostrictive layer has a positive piezoelectric coefficient;
wherein the second magnetostrictive layer has a negative piezomagnetic coefficient;
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
The first magnetostrictive layer and the second magnetostrictive layer include at least one from the group consisting of iron-silicon-boron-based alloys, nickel, iron, cobalt, and alloys thereof,
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
The piezoelectric layer comprises Pb (Zr, Ti) O ₃ ,
A ferroelectric-ferromagnetic composite laminate structure. The method of claim 1,
The first magnet member and the second magnet member, including at least one from the group consisting of neodymium (Nd), iron, cobalt, nickel, and alloys thereof,
A ferroelectric-ferromagnetic composite laminate structure. a composite layer including a first magnetostrictive layer, a piezoelectric layer positioned on the first magnetostrictive layer, and a second magnetostrictive layer positioned on the piezoelectric layer;
a first magnet member spaced apart from one side of the composite layer;
a first rotating member functioning as a rotating shaft for rotating the first magnet member; and
Containing; a second magnet member spaced apart from the other side of the composite layer
A ferroelectric-ferromagnetic composite laminate structure. 17. The method of claim 16,
A second rotating member functioning as a rotating shaft for rotating the second magnet member; further comprising,
A ferroelectric-ferromagnetic composite laminate structure.

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