Evidence for Phonon Scattering by Magnetic Two-Level Systems in Crystalline Spin-Glass EuxSr1−xS
During the last years, different experiments have given evidence for the spin-glass properties of the insulating system EuxSrl−xS and the phase diagram is well known . Recently, we have measured the low-temperature thermal conductivity K(T) of a x = 0.44 single crystal, and studied the effect of a magnetic field up to 7 T in the temperature range below 1 K . For this concentration, spin-glass behaviour is observed below the low-frequency freezing temperature Tg° = 1.8 K . From this study, we have suggested that the thermal phonons are resonantly scattered by low-lying magnetic excitations or “magnetic TLS” by analogy with the properties of structural glasses . We report here additional magneto thermal conductivity measurements carried out to test this hypothesis.
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