Local lattice distortion and photo-induced phase transition in transition-metal compounds with orbital degeneracy

T. Mizokawa, K. Takubo, T. Sudayama, Y. Wakisaka, N. Takubo, K. Miyano, N. Matsumoto, S. Nagata, T. Katayama, M. Nohara, H. Takagi, M. Ikeda, N. Kojima, M. Arita, H. Namatame, M. Taniguchi

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Abstract

Transition-metal compounds with spin, charge, and orbital degrees of freedom tend to have frustrated electronic states coupled with local lattice distortions and to show drastic response against external stimuli such as optical excitation. By means of photoemission spectroscopy, we have studied the electronic states of transition-metal compounds with corner-sharing and edge-sharing MX 6 octahedra (M=transition metal, X=O, S, Se, Br) such as prerovskite-type Pr 0.55(Ca 1-y Sr y ) 0.45MnO 3 and Cs 2Au 2Br 6, spinel-type CuIr 2S 4, and quasi-one-dimensional Ta 2NiSe 5. In the perovskite compounds with corner-sharing octahedra, the charge-orbital states are stabilized by Jahn-Teller or breathing-type lattice distortions and can be destroyed by optical excitations. On the other hand, the charge-orbital states in the edge-sharing systems are stabilized by dimer formation and tend to be robust against optical excitations. Based on the photoemission results, we will discuss effects of local lattice distortions on the excitonic states obtained by optical excitations as well as those in ground states.

Original languageEnglish
Pages (from-to)67-70
Number of pages4
JournalJournal of Superconductivity and Novel Magnetism
Volume22
Issue number1
DOIs
Publication statusPublished - 2009 Jan 1

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Keywords

  • Charge transfer
  • Excitonic insulator
  • Orbital degeneracy
  • Photo-induced phase transition
  • Photoemission

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Mizokawa, T., Takubo, K., Sudayama, T., Wakisaka, Y., Takubo, N., Miyano, K., Matsumoto, N., Nagata, S., Katayama, T., Nohara, M., Takagi, H., Ikeda, M., Kojima, N., Arita, M., Namatame, H., & Taniguchi, M. (2009). Local lattice distortion and photo-induced phase transition in transition-metal compounds with orbital degeneracy. Journal of Superconductivity and Novel Magnetism, 22(1), 67-70. https://doi.org/10.1007/s10948-008-0367-3