We use large-scale Monte Carlo computations to study the phase transitions between a two-component chiral p-wave superconductor and normal state in zero external magnetic field. We find a first-order phase transition from the normal state to a chiral superconducting state, due to interplay between vortices and domain walls.

We use large-scale Monte-Carlo simulations to study thermal fluctuations in chiral p-wave superconductors in an applied magnetic field in three dimensions. We consider the thermal stability of previously predicted unusual double-quanta flux-line lattice ground states in such superconductors. In previous works it was shown that, neglecting thermal fluctuations, a chiral p-wave superconductor forms a hexagonal lattice of doubly-quantized vortices, except extremely close to the vicinity of H c2 where double-quanta vortices split apart. We find dissociation of double-quanta vortices driven by thermal fluctuations. However, our calculations also show that the previous predictions of hexagonal doubly-quantized vortices, where thermal fluctuations were ignored, are very robust in the considered model.

Motivated by the recent experimental observation of an intermediate bosonic metallic state in the twodimensional superconductor-insulator transition at T = 0, we study an extended Bose-Hubbard model in the limit of a large number of particles per site. Using a representation of this in terms of two coupled XY models, we find, in addition to an insulating phase and a (2 + 1)D superfluid phase, two other phases. One phase is a 2D superfluid phase where a crossover from (2 + 1)D to 2D has taken place as a result of incipient charge ordering, signaled by θ disordering, and which is closely related to a supersolid phase. The other new phase is an edge metal state characterized by zero superfluid stiffness, zero charge ordering, and zero bulk compressibility. However, the edge compressibility of the system is nonzero. While we do not find any intermediate state with 2D metallic conductivity, we are able to connect these results to STM experiments on MoS 2 showing brims of finite density of states around the entire edge of 2D MoS 2 samples.