A Discrepancy in Thermal Conductivity Measurement Data of Quantum Spin Liquid β′-EtMe3Sb[Pd(dmit)2]2 (dmit = 1,3-Dithiol-2-thione-4,5-dithiolate)

Reizo Kato,Hengbo Cui,Masashi Uebe,Shigeki Fujiyama

doi:10.3390/cryst12010102

Abstract

A molecular Mott insulator β′-EtMe3Sb[Pd(dmit)2]2 is a quantum spin liquid candidate. In 2010, it was reported that thermal conductivity of β′-EtMe3Sb[Pd(dmit)2]2 is characterized by its large value and gapless behavior (a finite temperature-linear term). In 2019, however, two other research groups reported opposite data (much smaller value and a vanishingly small temperature-linear term) and the discrepancy in the thermal conductivity measurement data emerges as a serious problem concerning the ground state of the quantum spin liquid. Recently, the cooling rate was proposed to be an origin of the discrepancy. We examined effects of the cooling rate on electrical resistivity, low-temperature crystal structure, and 13C-NMR measurements and could not find any significant cooling rate dependence.

Highlights

Liquid β0 -EtMe3 Sb[Pd(dmit)2 ]2Quantum spin liquid (QSL) in a strongly frustrated spin system on a triangular lattice is characterized by the absence of long-range magnetic order or valence bond solid order among entangled quantum spins even at zero temperature [1,2]
The ground state of the Pd(dmit)2 salts is found to change among antiferromagnetic long-range order (AFLO), QSL, and charge order (CO), depending on the anisotropy of the triangular lattice that can be tuned by the choice of the counter cation [3]
The 13 C-enriched dmit ligand for 13 C-NMR measurements was synthesized from tetrachloroethylene-13 C1 (99 atom %, Sigma-Aldrich) that was converted to tetrathiooxalate for the reaction with CS2 [18]

Summary

Introduction

Quantum spin liquid (QSL) in a strongly frustrated spin system on a triangular lattice is characterized by the absence of long-range magnetic order or valence bond solid order among entangled quantum spins even at zero temperature [1,2]. An isostructural series of anion radical salts of a metal complex Pd(dmit). In crystals of β0 -Pd(dmit) salts with the space group C2/c, Pd(dmit) anion radicals are strongly dimerized to form a dimer with spin 1/2, [Pd(dmit)2 ]2 − (Figure 1). The anion radical layers and the non-magnetic cation layers are arranged alternately along the c axis. The ground state of the Pd(dmit) salts is found to change among antiferromagnetic long-range order (AFLO), QSL, and charge order (CO), depending on the anisotropy of the triangular lattice that can be tuned by the choice of the counter cation [3]. The QSL phase found in β0 -EtMe3 Sb[Pd(dmit)2 ]2 is situated between AFLO and CO phases [5,6]

Methods

Results

Conclusion