| Project/Area Number |
15340112
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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, School of Engineering, Professor, 大学院・工学系研究科, 教授 (30143382)
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| Co-Investigator(Kenkyū-buntansha) |
MIYASAKA Shigeki The University of Tokyo, School of Engineering, Research Associate, 大学院・工学系研究科, 助手 (70345106)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥15,500,000 (Direct Cost: ¥15,500,000)
Fiscal Year 2004: ¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 2003: ¥8,900,000 (Direct Cost: ¥8,900,000)
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| Keywords | magneto-electric optical effect / magneto-chiral effect / breakdown of time reversal and space inversion symmetry / x-ray nonreciprocal directional dichroism / troidal moment / GaFeO3 / Fe3O4 / スピン軌道相互作用 / カイラリテイー |
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| Research Abstract |
We have investigated the new magneto-optical effects termed "magneto-electric optical effect" and "magneto-chiral effect". In these optical effects, the optical response of the depolarized light depends on the direction of the propagator vector. We studied the optical features in the single crystals of the ferrimagnet, GaFeO3, and spinel-type Fe3O4 in order to clarify the mechanism of the magneto-electric optical effect and magneto-chiral one. GaFeO3 has spontaneous magnetization and electric polarization at low temperatures, indicating the breakdown of the space inversion symmetry and the time reversal one, while Fe3O4 has local space inversion symmetry.
The magneto-electric optical effect, i.e., the change of optical absorption upon the reversal of the light propagation direction, has been investigated for the polar ferrimagnet GaFeO3 in the energy region of 1.0-2.5 eV. Moreover, we have found a novel magneto-optical effect, termed x-ray nonreciprocal directional dichroism, that the x-ray absorption at around the K edge of an Fe ion depends on whether the x-ray propagation vector is parallel or antiparallel to the outer production of the magnetization and electric-polarization vectors in GaFeO3. These optical responses show the obvious dependence on the electric polarization and magnetization, suggesting the relationship between these optical effects and the toroidal moment. The x-ray nonreciprocal directional dichroism spectroscopy as demonstrated here can be a useful tool to prove the local magnetism in noncentroysymmetric systems such as magnetic interferences and nanostractures. We have found the x-ray nonreciprocal directional dichroism not only in GaFeO3 but also Fe3O4.
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