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Creation of room-temperature-multiferroic oxides and electric-field-controlled magnetization

室温多铁氧化物的制备和电场控制磁化

基本信息

批准号：
16360151
负责人：
GOMI Manabu
金额：
$ 7.74万
依托单位：
Nagoya Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

New materials exhibiting a large magnetoelectric effect due to coexistence of ferromagnetism and ferroelectricity at room temperature have been investigated. The following research results are obtained ;1.Electric-field-induced magnetization reduction and the mechanism in oxides exhibiting simultaneously ferromagnetism and ferroelectrics.(1)Coexistence of ferromagnetism and ferroelectricity observed in La, Mn : BaTiO_3 and BaTiO_3-LaMnO_3 composites are due to a small amount of ferromagnetic (La, Ba)MnO_3 phase precipitated into the grain boundaries or the inside of the ferroelectric grains.(2)The composites BaTiO_3-LaMnO_3 are materials simultaneously exhibiting ferroelectricity and a relatively ferromagnetic magnetization at room temperature. The density and dielectric properties of the composites markedly improved with the grain size of LaMnO_3 decreasing. When an electric field of 750 V/mm was applied to the composites, magnetization reduction as large as 25 % was observed for the … More first time.(3)An electric-field-induced magnetization reduction similar to that in the composites was observed for BaTiO_3/BaTiO_3-LaMnO_3 composite / BaTiO_3 structures where a composite was sandwiched between ferroelectric insulator BaTiO_3 layers. This suggests that the observed magnetization reduction is probably not due to thermal effect but intrinsic field-induced effect. Change of hole concentration in (La, Ba)MnO_3 induced by the dielectric polarization may be responsible for the magnetization reduction.(4)An electric-field-induced magnetization reduction of 2.2 % for the applied voltage of 4V was observed in a BaTiO_3/(La, Ba)MnO_3/BaTiO_3 layer structure. This is direct evidence showing the magnetization change to originate from the induced polarization.2.Search for new multiferroic materials(1)Pb(Zr, Ti)O_3-LaMnO_3 composites are new multiferroics with higher ferroelectric Curie temperature and larger polarization than BaTiO_3 system. It has been found for the first time that they exhibits a magnetization reduction as large as 30 % for a low applied electric field of 0.4 kV/mm at room temperature. Less

研究了室温下铁磁性和铁电性共存的大磁电效应新材料。取得了以下研究成果：1.同时具有铁电和铁磁性的氧化物中的电场诱导磁化还原及其机理。（1）在La，Mn：BaTiO_3和BaTiO_3-LaMnO_3复合材料中观察到的铁磁性和铁电性共存现象是由于少量铁磁性（La，Ba）MnO_3相析出到晶界或铁电晶粒内部所致。（2）BaTiO_3-LaMnO_3复合材料是在室温下同时具有铁电性和相对铁磁性的材料。随着LaMnO_3晶粒尺寸的减小，复合材料的致密度和介电性能显著提高。当向复合材料施加750 V/mm的电场时， ...更多信息首次(3)An在BaTiO_3/BaTiO_3-LaMnO_3复合材料/ BaTiO_3结构中，当复合材料夹在铁电绝缘体BaTiO_3层之间时，观察到与复合材料中类似的电场诱导磁化强度降低。这表明所观察到的磁化强度降低可能不是由于热效应，而是由于本征场诱导效应。介电极化引起的（La，Ba）MnO_3中空穴浓度的变化可能是磁化强度降低的原因。(4)An在BaTiO_3/（La，Ba）MnO_3/BaTiO_3层状结构中，当外加电压为4V时，观察到2.2%的电场诱导磁化强度降低。（1）Pb（Zr，Ti）O_3-LaMnO_3复合材料是一种新型的多铁性材料，与BaTiO_3系统相比，具有更高的铁电居里温度和更大的极化强度。首次发现，在室温下，对于0.4 kV/mm的低外加电场，它们表现出高达30%的磁化强度降低。少