Thermal Conductivity in Magnetic Superconductors

We present here an overview of thermal conductivity behavior in magnetic superconductors: rare-earth nickel borocarbide intermetallic compounds, RNi_{2}B_{2}C, and the 2122 rare-earth rutheno-cuprates. The borocarbide family of intermetallics exhibits the large variety of phenomena - only superconductivity (R = Y, Lu), coexistence of superconductivity and magnetic order (R = Tm, Er, Ho, Lu), only magnetic order (R = Tb, Gd), and heavy fermion behavior (R = Yb) - within the same crystal structure. The rutheno-cuprate Eu_{1.5}Ce_{0.5}RuSr_2Cu_{2}O_{10-\delta} exhibits coexistence of weak ferromagnetism and superconductivity at a surprisingly high temperature (\approx 45 K) and onset of antiferromagnetic order near 200 K. We demonstrate how coexistence of superconductivity and magnetic order in these compounds is releaved by the thermal conductivity studies.