Non-uniform state in 2D superconductors

We have investigated for the first time the complete temperature dependence of the upper critical field H-c2 in 2D layered superconductors taking both the orbital and Pauli limits into account. It is demonstrated that in 2D superconductors the formation of the non-uniform Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase gives rise to an unusual temperature dependence of H-c2: for fields exactly parallel to the layers, H-c2 has a linear temperature dependence as T --> 0; for any other field orientation, provided that the initial slope of the critical field at T = T-c is large, we predict at low temperature the appearance of a multiquanta vortex state, revealed by the oscillatory temperature dependence of H-c2. Such a new effect could be observed in low-T-c quasi-2D layered superconductors.