Magnetization and specific heat studies of the low temperature anomalies in terbium iron garnet Tb3Fe5O12

Abstract

The macroscopic magnetic properties of the terbium iron garnet (Tb3Fe5O12) single crystals were studied at low temperature by magnetizations MT (H) in magnetic fields up to 80 kOe and applied along the easy axis <111>. Maxima are observed near ∼ 65 and ∼ 47 K, respectively in the curves of the initial magnetic susceptibility χ0(T), and the parameter |b|(T) of the bH2 term are associated with the non linear variation of the MT (H) magnetizations. From the specific heat Cp(T) measurements, a great peak is observed near 57 K in the excess contribution of the Tb3+ ions Cpex(T) to Cp(T) which vanishes in the 170–208 K temperature range. The results are discussed with respect to the simultaneous signs of the “low-temperature point” TB predicted by Belov at 58 K and the ‘Schottky anomaly’ detected experimentally by the presence in the Cpex(T) curve of a 1/T2 term for T > TB.