1998 Fiscal Year Final Research Report Summary
OPTICAL SPECTRUM OF STRONGLY CORRELATED ELECTRON SYSTEMS
| Project/Area Number |
09440120
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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 |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | Kobe University |
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Principal Investigator |
NANBA Takao KOBE UNIVERSITY GRADUATE SCHOOL OF SCIENCE AND TECHNOLOGY PROFESSOR, 自然科学研究科, 教授 (30091721)
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| Co-Investigator(Kenkyū-buntansha) |
OKAMURA Hidekazu KOBE UNIVERSITY FACULTY OF SCIENCE ASSISTANT, 理学部, 助手 (00273756)
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| Project Period (FY) |
1997 – 1998
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| Keywords | strongly correlated electron system / Infrared microscopic study / energy gap / TmTe / YbB_<12> |
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| Research Abstract |
Infrared (IR) spectroscopic study is very useful method to investigate the electronic structure of materials with strong electron correlation because its has a very low photon energy and therefore it makes possible the low energy optical excitation in the solids. However, most of interesting materials grow in a very small single crystal-line state or in polycrystalline state with definite roughness. Therefore it is difficult to perform IR spectroscopic measurement with such specimens. In such a case, IR microscopic measurement seems to work well because, of microscope makes it possible to measure optical spectrum with a very tiny specimens. We performed reflection and transmission measurements on these materials by using IR microscope combined with IR interferometer (Bruker 66v) in the very wide energy region from far-infrared to ultraviolet.
In this study, the following results were obtained,
(1) From the transmission measurement on TmTe and SmTe which are both a semiconductor with a small energy gap in the IR region, we found that TmTe has a characteristic absorption structure at 150meV in the absorption edge. On the other hand, SmTe showed a simple absorption edge. The electronic structure close to the fermi level are different from each other althpough the electron configuration of both materials are very similar.
(2) YbB_<12> is recognized as a typical Kondo-insulator which exhibits a formation of small energy gap only at low temperature. From the reflection measurement with an accuracy within 1% in the reflectivity on Yb_<1-x>Lu_xB_<12> single crystal, we foud that the gradual substitution of non-magnetic Lu with Yb gives rise to an appearance of a new band in the band gap in YbB_<12> at low temperature.
(3) IR microscopic measurement was confirmed to be very effective in the study of the electronic structure of strongly correlated electron systems.
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Research Products
(4 results)
