Investigation on the magnetocaloric effect in DyNi_2, DyAl_2 and Tb_(1-n)Gd_nAl_2 (n = 0, 0.4, 0.6) compounds

摘要

The magnetocaloric effect (MCE) in the DyNi_2, DyAl_2 and Tb_(1-n)Gd_nAl_2 (n = 0, 0.4, 0.6) was theoretically investigated in this work. The DyNi_2 and DyAl_2 compounds are described considering a model Hamiltonian which includes the crystalline electrical field anisotropy. The anisotropic MCE was calculated changing the magnetic field direction from <111> to <001> in DyNi_2 and from < 100> to <011 > in DyAl_2. The influence of the second- and first-order spin-reorientation phase transitions on the MCE that occurs in these systems is discussed. For the calculations of the MCE thermodynamic quantities in the Tb_(1-n)Gd_nAl_2 systems we take into account a two sites magnetic model, and good agreement with the available experimental data was obtained.