2006 Fiscal Year Final Research Report Summary
Creation of room-temperature-multiferroic oxides and electric-field-controlled magnetization
| Project/Area Number |
16360151
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | Nagoya Institute of Technology |
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Principal Investigator |
GOMI Manabu Nagoya Institute of Technology, Graduate school of engineering, Professor, 工学研究科, 教授 (80126276)
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| Co-Investigator(Kenkyū-buntansha) |
OOSATO Hitoshi Nagoya Institute of Technology, Graduate school of engineering, Professor, 工学研究科, 教授 (20024333)
ADACHI Nobuyasu Nagoya Institute of Technology, Graduate school of engineering, Associate professor, 工学研究科, 助教授 (90262956)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Multiferroics / Perovskite oxide / Magnetoelectric effect / BaTiO_3 / Ceramic composite / Ferroelectric magnet / Ferroelectromagnetic materials |
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| Research Abstract |
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
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