Disorder-driven two-dimensional quantum phase transitions in Li _x MoS ₂

Abstract 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 Li _x MoS ₂ 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.