Disorder-driven two-dimensional quantum phase transitions in Li x MoS2

Quantum phase transition (QPT) is the keystone in understanding the quantum state of matter. Here we report observation of QPT and its evolution in nanosheets of LixMoS2 with various degrees of disorder introduced by progressive thermal annealing. The material exhibits onset of superconducting transition at temperatures ranging between 3 and 6 K. We show that the angular dependence of the upper critical field is well described by Tinkham's (2D) model. Finite-size scaling analysis reveals that the pristine samples with predominantly T/T' phases exhibit magnetic-field driven superconductor-to-metal QPT. We further show that annealed samples with a higher content of 2H phase exhibit QPT with diverging critical exponents similar to the recently reported behaviours of highly crystalline 2D superconductors.