Photoemission study of the metal-insulator transition in NiS2-xSex

Phys. Rev. B 58, 9611 – Published 15 October 1998
K. Mamiya, T. Mizokawa, A. Fujimori, T. Miyadai, N. Chandrasekharan, S. R. Krishnakumar, D. D. Sarma, H. Takahashi, N. Môri, and S. Suga

Abstract

We have studied the electronic structure of NiS2-xSex, which undergoes a metal-insulator transition as functions of composition x and temperature, by means of photoemission and inverse-photoemission spectroscopy. Spectral changes across the transition near the Fermi level (EF) (particularly within 100 meV of EF) have been interpreted as due to a “semimetallic” closure of the band gap in going from the insulating phase to the antiferromagnetic metallic phase. On the other hand, there is also composition- and temperature-dependent spectral weight transfer over a wider energy range of 0.51 eV, indicating significant correlation effects. Photoemission intensity just below EF remains high in the insulating phases, indicating that the carrier number is large at high temperatures and that the activation-type transport is due to the activated mobility rather than the activated carrier number.

DOI: http://dx.doi.org/10.1103/PhysRevB.58.9611

  • Received 6 April 1998
  • Published in the issue dated 15 October 1998

© 1998 The American Physical Society

Authors & Affiliations

K. Mamiya*, T. Mizokawa, and A. Fujimori

  • Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan

T. Miyadai

  • Faculty of Fine Arts, Dohto University, Kita-Hiroshima 061-11, Japan

N. Chandrasekharan, S. R. Krishnakumar, and D. D. Sarma

  • Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India

H. Takahashi

  • College of Humanities and Sciences, Nihon University, Setagaya-ku, Tokyo 156, Japan

N. Môri

  • Institute for Solid State Physics, University of Tokyo, Roppongi, Tokyo 106, Japan

S. Suga

  • Department of Material Physics, Faculty of Engineering Science, Osaka University, Toyonaka 560, Japan

  • *Present address: Institute for Material Structure Science, High Energy Accelerator Research Organization, Oho, Tsukuba, Ibaraki 305, Japan.

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