Josephson Vortex States in Intermediate Fields

Abstract

Motivated by recent resistance data in high T_c superconductors under magnetic fields parallel to the CuO layers, we address two key issues on the Josephson-vortex phase diagram, an appearance of structural transitions on the observed first order transition (FOT) curve in intermediate fields and of a lower critical point of the FOT line. The structural transitions reflected on the thermal transition curve in YBCO are identified based on our mean field calculation, and it is argued that a lower critical point more easily occurs in the present B ⊥ c case compared with that in B || c case.