MAGNETIC-FIELD DEPENDENCE OF THE THERMAL-CONDUCTIVITY IN EUXSR1-XS

The thermal conductivity kappa of two Eu//xSr//1// minus //x single crystals (x equals 0. 25 and 0. 54) was measured between 1. 5 and 25 K. In magnetic fields of approximately equals 7 T kappa is enhanced for temperatures up to 20 K with respect to kappa (B equals 0). At 1. 5 K, where the relative increase kappa (B)/ kappa (0) is largest, this ratio is 1. 5 for x equals 0. 54 and approximately equals 4 for x equals 0. 25. Two possible mechanisms for this effect, i. e. , freezing of phonon scattering by magnetic excitations in a magnetic field, and heat transport by field-induced magnons, are discussed.