Optical and photoelectrical studies on anisotropic metal-insulator transition of RuAs

Yuki Nakajima, Zenjiro Mita, Hiroshi Watanabe, Yoshiyuki Ohtsubo, Takahiro Ito, Hisashi Kotegawa, Hitoshi Sugawara, Hideki Tou, and Shin-ichi Kimura
Phys. Rev. B 100, 125151 – Published 23 September 2019

Abstract

The anisotropic changes in the electronic structure of a metal-to-insulator transition (MIT) material, RuAs, with a two-step phase transition are reported by using polarized optical conductivity σ(ω) spectra, angle-integrated photoelectron (PE) spectra, and band calculations based on the local-density approximation (LDA). Both the PE and σ(ω) spectra, not only in the high-temperature (HT) phase but also in the low-temperature (LT) phase as well as the energy gap formation owing to the MIT, were almost consistent with those derived from the LDA band calculations, so the fundamental electronic structure in the HT and LT phases can be explained without electron correlations. However, the electronic structure in the middle phase between the HT and LT phases has not been clarified. The polarized σ(ω) spectra revealed not only the anisotropic energy gap formation but also the anisotropic gap-opening temperature; that is, the energy gap along the c axis in the HT phase starts to open near the higher transition temperature, but that along the b axis opens below the lower transition temperature. The finding suggests that the two-step MIT originates from the anisotropic energy gap formation.

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  • Received 9 August 2019
  • Revised 11 September 2019

DOI:https://doi.org/10.1103/PhysRevB.100.125151

©2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Yuki Nakajima1, Zenjiro Mita2, Hiroshi Watanabe2,1, Yoshiyuki Ohtsubo2,1, Takahiro Ito3,4, Hisashi Kotegawa5, Hitoshi Sugawara5, Hideki Tou5, and Shin-ichi Kimura2,1,*

  • 1Department of Physics, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
  • 2Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
  • 3Nagoya University Synchrotron Radiation Research Center, Nagoya University, Nagoya 464-8603, Japan
  • 4Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
  • 5Department of Physics, Graduate School of Science, Kobe University, Kobe 657-8501, Japan

  • *kimura@fbs.osaka-u.ac.jp

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Issue

Vol. 100, Iss. 12 — 15 September 2019

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