Heat-capacity anomaly due to spin reorientation and thermodynamic functions of ErFeO3 and TmFeO3

Heat capacities of orthoferrites, ErFeO3 and TmFeO3, have been measured below room temperature by adiabatic calorimetry. A broad but definite anomaly due to the spin reorientation phenomenon was successfully detected in the expected temperature range (ca. 90 K). The results are compared with a vast anomaly reported for YbFeO3. The temperature dependence of the electric quadrupole splitting of the Fe nuclear levels was determined by Mossbauer spectroscopy through the spin reorientation, A heat capacity anomaly centered at 3.60 K due to the magnetic ordering of Er3+ ions was clearly detected. Some Schottky anomalies were resolved and energy splittings involved were roughly estimated. Some thermodynamic functions are derived and tabulated. (C) 2001 Elsevier Science B.V, All rights reserved.