Abstract
An angle-resolved photoemission spectroscopy (ARPES) study is reported on a Mott insulator in which () 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 which are different from wave vectors dominating low-energy spin excitations at low temperatures. The unexpected difference between and 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.
- Received 7 August 2009
DOI:https://doi.org/10.1103/PhysRevLett.104.226404
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