Separation between Low-Energy Hole Dynamics and Spin Dynamics in a Frustrated Magnet

Kou Takubo, Yusuke Nambu, Satoru Nakatsuji, Yuki Wakisaka, Takaaki Sudayama, David Fournier, Giorgio Levy, Andrea Damascelli, Masashi Arita, Hirofumi Namatame, Masaki Taniguchi, and Takashi Mizokawa
Phys. Rev. Lett. 104, 226404 – Published 3 June 2010

Abstract

An angle-resolved photoemission spectroscopy (ARPES) study is reported on a Mott insulator NiGa2S4 in which Ni2+ (S=1) ions form a triangular lattice and the Ni spins do not order even in its ground state. The first ARPES study on the two-dimensional spin-disordered system shows that low-energy hole dynamics at high temperatures is characterized by wave vectors QE which are different from wave vectors QM dominating low-energy spin excitations at low temperatures. The unexpected difference between QE and QM is deeply related to charge fluctuation across the Mott gap in the frustrated lattice and is a key issue to understand the spin-disordered ground states in Mott insulators.

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  • Received 7 August 2009

DOI:https://doi.org/10.1103/PhysRevLett.104.226404

©2010 American Physical Society

Authors & Affiliations

Kou Takubo1, Yusuke Nambu2, Satoru Nakatsuji2, Yuki Wakisaka1, Takaaki Sudayama1, David Fournier3, Giorgio Levy3, Andrea Damascelli3, Masashi Arita4, Hirofumi Namatame4, Masaki Taniguchi4,5, and Takashi Mizokawa1,4

  • 1Department of Physics & Department of Complexity Science and Engineering, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8561, Japan
  • 2Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
  • 3Department of Physics and Astronomy, University of British Columbia, Vancouver, B.C., V6T 1Z4, Canada
  • 4Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashihiroshima, Hiroshima 739-0046, Japan
  • 5Graduate School of Science, Hiroshima University, Higashihiroshima, Hiroshima 739-8526, Japan

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Issue

Vol. 104, Iss. 22 — 4 June 2010

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