Understanding the magnetic response of the Quantum spin liquid compound 1T-TaS2

TL;DR

This study investigates the magnetic susceptibility of 1T-TaS2, revealing local magnetic moment formation in the nearly commensurate charge density wave phase and evidence of a random singlet state at low temperatures.

Contribution

It provides new insights into the temperature-dependent magnetic behavior and local moment formation in 1T-TaS2, a candidate quantum spin liquid material.

Findings

Local moments form above the Mott insulating transition.

Susceptibility deviates from Curie-Weiss law in the commensurate phase.

Power law behavior indicates a random singlet state below 10 K.

Abstract

1T-tantalum disulphide (1T-TaS2) is a promising material to realize quantum spin liquid state and fractional excitations. Here, we take a closer look on the temperature dependent magnetic susceptibility of 1T-TaS2 at low magnetic fields to understand the formation of local magnetic moment in this system and its response as a function of temperature and field. We found that the susceptibility increases with reduction in the temperature even in the nearly commensurate charge density wave (CDW) phase, which exhibits metallic conductivity and hence is expected to exhibit temperature independent Pauli paramagnetic susceptibility. Therefore, it indicates that local moment starts forming in the nearly commensurate CDW phase itself, which is well above the temperature where the evidence of Mott insulating state is found in resistivity measurement. In the commensurate CDW phase, temperature dependence of susceptibility significantly deviates from the Curie-Weiss law and does not show the magnetic properties expected from S = 1/2 spin on a two dimensional triangular lattice. Below T = 10 K, susceptibility follows a power law dependence on the temperature, which indicates towards the formation of random singlet state in 1T-TaS2.