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OPTICAL SPECTRUM OF STRONGLY CORRELATED ELECTRON SYSTEMS

Research Project

Project/Area Number 09440120
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field 固体物性Ⅰ(光物性・半導体・誘電体)
Research InstitutionKobe University

Principal Investigator

NANBA Takao  KOBE UNIVERSITY GRADUATE SCHOOL OF SCIENCE AND TECHNOLOGY PROFESSOR, 自然科学研究科, 教授 (30091721)

Co-Investigator(Kenkyū-buntansha) OKAMURA Hidekazu  KOBE UNIVERSITY FACULTY OF SCIENCE ASSISTANT, 理学部, 助手 (00273756)
Project Period (FY) 1997 – 1998
Project Status Completed (Fiscal Year 1998)
Budget Amount *help
¥13,700,000 (Direct Cost: ¥13,700,000)
Fiscal Year 1998: ¥6,000,000 (Direct Cost: ¥6,000,000)
Fiscal Year 1997: ¥7,700,000 (Direct Cost: ¥7,700,000)
Keywordsstrongly correlated electron system / Infrared microscopic study / energy gap / TmTe / YbB_<12> / 赤外顕微鏡反射透過法
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.

Report

(3 results)
  • 1998 Annual Research Report   Final Research Report Summary
  • 1997 Annual Research Report
  • Research Products

    (5 results)

All Other

All Publications (5 results)

  • [Publications] Hidekazu Okamura: "Optical conductivity of the Kondo insulator YbB12:Gap formation and low-energy excitation" Physical Review. B58(12). R7496-R7499 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] Takao Nanba: "High-pressure solid state spectroscopy atUVSOR by Infrared Synchrotron Radiation" IL NUOVO CIMENTO, 16 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] HIDEKAZU OKAMURA: "Optical conductivity of the Kondo insulator YbB12 : Gap formation and low-energy excitation" Physical Review. B58 (12). R7496-R7499 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] TAKAO NANBA: "High-pressure solid state spectroscopy at UVSOR by Infrared Synchrotron Radiation" IL NUOVO CIMENTO. 20 (4). 397-413 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] Takao Nanba: "High-pressure solid state spectroscopy atUVSOR by Infrared Synchrotron Radiation" IL NUOVO CIMENTO, 16 (1998)

    • Related Report
      1998 Annual Research Report

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Published: 1997-04-01   Modified: 2020-05-15  

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