Specific-heat anomaly of a ferromagnet in finite magnetic fields

Abstract

Low-temperature specific-heat data of two ferromagnetic EuSrS samples (x=1 and 0.7) in external magnetic fields between 0 and 50 mT are reported. It is observed that the sharp zero-field anomaly persists in finite fields with the peak temperature shifting towards lower temperature with increasing field. This apparent decrease of the Curie temperature, previously found in other systems, is explained in terms of demagnetization effects alone, the field dependence of the peak temperature being determined by ß, the critical exponent of the spontaneous magnetization.