| Project/Area Number |
17K05521
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Condensed matter physics II
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| Research Institution | National Institute for Materials Science |
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Principal Investigator |
SAKURAI Hiroya 国立研究開発法人物質・材料研究機構, エネルギー・環境材料研究拠点, グループリーダー (60421400)
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2019: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2018: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2017: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Keywords | t2g軌道 / 正方対称場 / Cr酸化物 / クロム酸化物 / t2g電子系 / 正方格子 / 磁性 / 高圧物性 / 高圧合成 / t2g電子 / Mott絶縁体 / 新物質 / 蜂の巣格子 / 強相関電子系 |
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| Outline of Final Research Achievements |
Sr3Cr2O7 and Sr4Cr3O10 show structural transitions. Our detailed analysis of their crystal structures revealed that, for both compounds, the dxy orbital of Cr ions is most likely lower in energy than the doubly degenerated dyz and dzx orbitals. Two 3d electrons of Cr ion occupy both the dxy orbital and the degenerated orbitals, which creates the orbital degree of freedom. So, the two compounds are expected to have orbital ordered states. The orbital ordering is also theoretically expected for alpha-Sr2CrO4 although temperature dependence of its magnetic susceptibility is largely different from that of Sr3Cr2O7 and Sr4Cr3O10. Furthermore, the similar orbital ordering is expected also for alpha-Sr2VO4 with 3d1 electronic configuration, as the degenerated orbitals are lower in energy than the dxy orbital for the V oxide. Therefore, the t2g orbitals in tetragonal crystal fields may tend to have the orbital degree of freedom.
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| Academic Significance and Societal Importance of the Research Achievements |
eg軌道のスピンと軌道の状態はMn酸化物を中心に非常に詳しく調べられている。一方でt2g軌道が主役となる場合については立方対称場を基本とする場合は詳しく調べられているが、正方対称場中の場合は不十分であった。本研究により正方対称場でも立方対称場の場合と同様に軌道秩序状態を好むことが分かりd電子系の物理の理解が進んだ。
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