Critical spin liquid versus valence-bond glass in a triangular-lattice organic antiferromagnet.

ABSTRACT: In the quest for materials with unconventional quantum phases, the organic triangular-lattice antiferromagnet κ-(ET)₂Cu₂(CN)₃ has been extensively discussed as a quantum spin liquid (QSL) candidate. The description of its low temperature properties has become, however, a particularly challenging task. Recently, an intriguing quantum critical behaviour was suggested from low-temperature magnetic torque experiments. Here we highlight significant deviations of the experimental observations from a quantum critical scenario by performing a microscopic analysis of all anisotropic contributions, including Dzyaloshinskii-Moriya and multi-spin scalar chiral interactions. Instead, we show that disorder-induced spin defects provide a comprehensive explanation of the low-temperature properties. These spins are attributed to valence bond defects that emerge spontaneously as the QSL enters a valence-bond glass phase at low temperature. This theoretical treatment is applicable to a general class of frustrated magnetic systems and has important implications for the interpretation of magnetic torque, nuclear magnetic resonance, thermal transport and thermodynamic experiments.

SUBMITTER: Riedl K 

PROVIDER: S-EPMC6561973 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature