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

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, C_m(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 T^3/2 in support of the spin wave excitations predictions.