Charge-4e superconductivity from nematic superconductor: study based on a generalized XY model

Charge-4e superconductivity is an intriguing state of matter that has gained considerable attention in recent years. Previous studies have suggested that this exotic phase can arise from multicomponent superconductors such as the pair-density-wave or the nematic superconductor. In this work, we propose a concrete model on the honeycomb lattice with a nematic superconducting ground state. With Monte Carlo simulations, we reveal a complex and promising finite-temperature phase diagram which not only includes the charge-4e phase but also a new phase exhibiting both nematic and charge-4e quasi-long-range orders. Furthermore, we demonstrate that the proliferation of domain walls, in addition to the vortices, also plays a significant role in the phase transitions involving charge-4e. Our findings offer valuable insights into the role of domain walls and the interplay between superconducting and nematic vortices in the charge-4e superconductivity phenomenon.