Abstract
We have investigated for the first time the complete temperature dependence of the upper critical field Hc2 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 Hc2: for fields exactly parallel to the layers, Hc2 has a linear temperature dependence as T → 0; for any other field orientation, provided that the initial slope of the critical field at T = Tc is large, we predict at low temperature the appearance of a multiquanta vortex state, revealed by the oscillatory temperature dependence of Hc2. Such a new effect could be observed in low-Tc quasi-2D layered superconductors.