The low temperature specific heat of single crystal Er-Al2 compound

Abstract

The low temperature heat capacity of the ErAl2 single crystal compound have been measured in the temperature 2– 40 K using a modified adiabatic continues heating technique. The magnetic contributions to the total specific heat were extracted using similar but nonmagnetic “lattice blank”, which gives a good description of the non-magnetic contributions to the heat capacities. The magnetic specific heat exhibits large anomaly at the highly cooperative magnetic phase transition, which lies at about 12 K. A broad Schottky anomaly was shown centered at about 30 K. The magnetic contributions to the heat capacity of the ErAl2 compound, Cm(T) have been calculated using mean field approximation. The Hamiltonian has been taken to be the sum of crystal field and isotropic exchange terms. A computer program based on the molecular field approximation has been written to calculate the crystal field levels and the magnetic contributions to the heat capacity as a function of temperature in the ErAl2 compound. The critical exponent analysis showed that α′ ≈ α and A′/A ≈ 1.9. The low temperature magnetic specific heats behave as T3/2 in support of the spin wave excitations predictions.