| Project/Area Number |
17340104
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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 |
Condensed matter physics II
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TOKURA Yoshinori The University of Tokyo, Graduated School of Engineering, professor (30143382)
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| Co-Investigator(Kenkyū-buntansha) |
ONOSE Yoshinori The University of Tokyo, Graduated School of Engineering, Lecturer (80436526)
IGUCHI Satoshi The University of Tokyo, Graduated School of Engineering, Research Associate (50431789)
花咲 徳亮 東京大学, 大学院・工学系研究科, 講師 (70292761)
宮坂 茂樹 東京大学, 大学院工学系研究科, 助手 (70345106)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥16,650,000 (Direct Cost: ¥15,300,000、Indirect Cost: ¥1,350,000)
Fiscal Year 2007: ¥5,850,000 (Direct Cost: ¥4,500,000、Indirect Cost: ¥1,350,000)
Fiscal Year 2006: ¥5,200,000 (Direct Cost: ¥5,200,000)
Fiscal Year 2005: ¥5,600,000 (Direct Cost: ¥5,600,000)
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| Keywords | Magnetoelectric effect / Ferroelectrics / Ferromagnets / Cross-correlation / Strongly-correlated electronics / Magnetic ferroelectrics / 誘電体 / 誘電体物性 / 磁性 / 光学的電気磁気効果 / 電気分極フロップ / スパイラル、ヘリカル磁気構造 / マンガン酸化物 |
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| Research Abstract |
In this study we have developed the magnetic ferroelectric oxides which may host the gigantic magnetoelectric effect. We could control the electric polarization in the materials by magnetic field as the gigantic magnetoelectric effect, and some times the magnetic structure itself by electric field as the reciprocal effect. The gigantic optical magnetoelectric (magneto-chiral) effect was also observed.
We have aimed at the realization of the gigantic magnetoelectric effect, and found new magnetic ferroelectrics based on the time and space symmetry breaking, multicriticality of electronic phases, and the chirality in lattices and frustration of spins. We have found magnetic ferroelectricity in perovskite type manganites RMnO_3 and Pr(Sr, Ca)_2Mn_2O_7, spinets CoCr_2O_4, and low dimensional frustration oxides Cu(Fe, Al)O_2, and LiCu_2O_2, in which polarization was controlled by magnetic field. Furthermore the change of the magnetic chirality with external electric field was confirmed by synchrotron x ray radiation, and neutron scattering studies.
The gigantic optical magnetoelectric effect has various potentials for the new optical devices such as an optical isolator in the optical communication. We have succeeded in the synthesis of the single crystals of the rare earth metal doped (Ba, Sr)TiO_3, La_2Ti_2O_7 and so on, and observed the emission spectra due to the optical magnetoelectric effect. Moreover, we observed the optical magnetoelectric response stem from the magnetic interface of the tailor-made tricolor superlattice of LaMnO_3/SrMnO_3/LaAlO_3.
In collaboration with theory groups, we show the origins of these effects are the unconventional magnetoelectric coupling characterized by the quantities of spin current and toroidal moment. We believe that this made a great contribution to the progress of the new spintronics.
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