Understanding the magnetic response of the Quantum Spin Liquid compound 1T-TaS2

1T-tantalum disulphide (1T-TaS2) is a promising material to realize quantum spin liquid state. 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 reducing 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. It indicates that local moment starts forming in the nearly commensurate CDW phase itself, which is well above the temperature where evidence of Mott insulating state appears in resistivity measurement. In the commensurate CDW phase, susceptibility significantly deviates from the Curie-Weiss law. Below T = 10 K, temperature dependence of susceptibility indicates the formation of random singlet state in 1T-TaS2.