Magnetic field hysteresis of thermal conductivity in type-I and typy-II superconductors

This study investigated the magnetic field ($H$) dependence of thermal conductivity ($\kappa$) in type I (Pb) and type II (Nb) superconductors. The $\kappa$ of Nb displayed hysteresis, showing a local minimum during increasing $H$ process but not during decreasing $H$ process. Different magnetic field dependencies were observed in Pb with varying purity: $\kappa$ of 3N-Pb exhibited broad hysteresis, while that of 5N-Pb showed hysteresis similar to 3N-Nb.