2013 Fiscal Year Final Research Report
Study on the mechanism of metal-insulator transition in the pyrochlore iridates
| Project/Area Number |
23540417
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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 | Kyushu Institute of Technology |
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Principal Investigator |
KAZUYUKI Matsuhira 九州工業大学, 工学(系)研究科(研究院), 准教授 (40312342)
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| Co-Investigator(Kenkyū-buntansha) |
KAZUAKI Iwasa 東北大学, 大学院・理学研究科, 准教授 (00275009)
KEITARO Kuwahara 茨城大学, 理工学研究科, 准教授 (90315747)
TAKUMI Hasegawa 広島大学, 大学院・総合科学研究科, 助教 (20508171)
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| Project Period (FY) |
2011 – 2013
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| Keywords | パイロクロア酸化物 / イリジウム酸化物 / 金属絶縁体転移 / 中性子散乱 / ラマン散乱 / X線回折 |
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| Research Abstract |
We investigated the mechanism of metal-insulator transition in the pyrochlore iridates by using neutron scattering, Raman scattering, X-ray diffraction, and thermal expansion measurements.
We revealed the magnetic structure of low temperature phase is "all-in all-out" for Nd2Ir2O7; this is first discovery. This magnetic structure has a unique character. There is no change of structural symmetry phase below transition temperature. Raman scattering and XRD measurements support this magnetic structure. Furthermore, we found the change of lattice parameter caused by the metal-insulator transition is small. On the other hand, the results of Raman scattering for Sm2Ir2O7 and Eu2Ir2O7 suggest structural change although cubic symmetry keeps. The structure in the low temperature phase is future subjects.
In addition, in this research process, we discovered giant magnetoresistance effect for Nd2Ir2O7.
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