Upper critical field of κ-(ET)2Cu[N(CN)2]Br under parallel magnetic fields

Abstract The upper critical field H c2 of κ -(ET) 2 Cu[N(CN) 2 ]Br under magnetic fields parallel to the superconducting layer has been determined based on the temperature dependence of the out-of-plane resistance. The H c2 exceeds the Pauli paramagnetic limit value based upon a weak coupling BCS model and tends to increase further toward lower temperatures.