Calorimetry of DyxY3−xAl5O12 garnet solid solutions in magnetic field

Abstract

We report the caloric and magnetocaloric properties of the DyxY3−xAl5O12 garnet single crystals (x = 0, 0.15, 0.5, 1, 1.5, 2.25, 3) studied within a large temperature range at magnetic fields up to 70 kOe. Heat capacity at zero field revealed that the Schottky anomalies ascribed to magnetic splitting the ground Kramers doublet of Dy3+ ions induced by neighbor ions. The low-temperature heat capacity was fitted by a sum of the Debye and Schottky contributions. The antiferromagnetic transition above 1.9 K was observed only for the pure dysprosium aluminum garnet. The shifts of the Schottky anomalies in magnetic fields agreed with strong anisotropy of the g-factor of Dy3+ ions in the c-sites. The Dy3+ ions in the non-stoichiometric positions caused additional weak anomalies in the heat capacity. The heat capacity for the garnet with x = 1 demonstrated strong clustering for this particular composition. The results obtained showed that the measurements of the heat capacity in magnetic field can be used to get information on substitutional disorder and non-stoichiometry in solid solutions. The magnetic entropy was evaluated for the dysprosium-comprising garnets. The pronounced magnitude of the magnetic entropy owing to the Schottky anomalies shows the applicability of the mixed dysprosium yttrium garnets to adiabatic refrigerators.