New ground states in unconventional superconductors: Broken translational and time-reversal symmetry

Abstract

We explore the spatial structure of novel ground states which can arise in unconventional superconductors. If the coefficients in the Ginzburg-Landau functional are in the appropriate range, the free energy, even in zero applied field, is minimized by a state with a spatially varying order parameter. This variation leads to supercurrents, which generate substantial magnetic fields. The interactions between the vector potential and the order parameter are responsible for the net lowering of the free energy. We use a simulated annealing technique to find numerically the minima of the Ginzburg-Landau functional.