Separation between low-energy hole dynamics and spin dynamics in a frustrated magnet.
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 Q(E) which are different from wave vectors Q(M) dominating low-energy spin excitations at low temperatures. The unexpected difference between Q(E) and Q(M) 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.
Takubo
Kou
K
Department of Physics, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8561, Japan.
Nambu
Yusuke
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Nakatsuji
Satoru
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Wakisaka
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Sudayama
Takaaki
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Fournier
David
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Levy
Giorgio
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Damascelli
Andrea
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Arita
Masashi
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Namatame
Hirofumi
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Taniguchi
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Mizokawa
Takashi
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