Abstract :
Anomalies in the heat capacity due to spin reorientation transitions have been successfully detected for two orthoferrites by chopped-light ac calorimetry on single-crystals. Onset and completion of the spin reorientation were clearly detected as jumps in heat capacity at 82 and 89 K for TmFeO3 and at 53 and 59 K for HoFeO3. The magnitude of the anomalies is less than 1% with respect to the total heat capacity at the transition temperatures. The shapes of the anomalies are compared with available theoretical models.
