title: Anomalous metallic state in the vicinity of metal to valence-bond solid insulator transition in LiVS2.
abstract: We investigate LiVS2 and LiVSe2 with a triangular lattice as itinerant analogues of LiVO2 known for the formation of a valence-bond solid (VBS) state out of an S=1 frustrated magnet. LiVS2, which is located at the border between a metal and a correlated insulator, shows a first order transition from a paramagnetic metal to a VBS insulator at Tc approximately 305 K upon cooling. The presence of a VBS state in the close vicinity of insulator-metal transition may suggest the importance of itinerancy in the formation of a VBS state. We argue that the high temperature metallic phase of LiVS2 has a pseudogap, likely originating from the VBS fluctuation. LiVSe2 was found to be a paramagnetic metal down to 2 K.
authors.affiliation: Department of Advanced Materials, University of Tokyo, Kashiwa 277-8561, Japan. nk2u@cms.mail.virginia.edu
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authors.lastname: Katayama
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authors.lastname: Takagi