Non-saturating upper critical field of organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Cl

Abstract The layered superconductor κ -(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl in the magnetic field applied strictly parallel to the superconducting plane shows the upper critical field exhibiting non-saturating behavior toward 0 K. The relation to the spatially modulated order-parameter state predicted by Fulde–Ferrell and Larkin–Ovchinnikov is argued.