Molecular Quasi-Triangular Lattice Antiferromagnets

Abstract

Reizo Kato Condensed Molecular Materials Laboratory, RIKEN, Wako-shi, Saitama 3510198, JapanTetsuaki Itou Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, JapanWe demonstrate here the possibility of a quantum spin-liquid state and related phenomena in a 2D molecular Mott system based on the Pd(dmit)2 (dmit = 1,3-dithiole-2-thione-4,5-dithiolate) molecule. The quantum spin liquid is a spin state in which quantum fluctuations prevent order, leading to liquid-like properties among the spins, even at absolute zero temperature. It was proposed early on that this state can be realized in quantum spin systems on frustrated lattices [1]. In frustrated lattices, there exist a huge number of different classical spin configurations with nearly the same energy. Quantum mechanics causes resonance between these degenerate configurations and consequently leads to a liquid-like wavefunction. In this state, all the spins form spin-singlet pairs, i.e., valence bonds, and they fluctuate between many different configurations. The quantum spin liquid is a long-sought state of matter that has attracted much theoretical attention. However, one of the difficulties in the search for the quantum spin liquid is that there are few candidates in real materials: only “two” are known in molecular systems, one being found in the Pd(dmit)2 compounds.