New paradigm for a magnetic field driven SIT*

We show that while orbital magnetic field and disorder, acting individually weaken superconductivity, acting together they produce an intriguing evolution of a two-dimensional type-II s-wave superconductor[1-4]. For weak disorder, the critical field at which the superfluid density collapses matches the field at which the superconducting energy gap gets suppressed to zero. With increasing disorder, these two fields diverge from each other creating a pseudogap region. We predict a transformation from "Abrikosov" metallic vortex cores for weak disorder to "Josephson" vortices with gapped and insulating cores for higher disorder. Our results explain the disappearance of the celebrated zero-bias Caroli-de Gennes-Matricon (CdGM) peak in experiments on disordered superconductors. The emergence of the pseudogap phase provides a natural understanding of the long standing puzzle of the gigantic magnetoresistance peak observed as a function of magnetic field in thin disordered superconducting films.