Study of the magnetic and magnetocaloric properties of amorphous alloys formed by the ErxFe100−x series

Abstract

In this work, we investigate the magnetic and thermodynamic properties and the magnetocaloric effect of amorphous alloys formed from the series ${\mathrm{Er}}_x{\mathrm{Fe}}_{100-x}$. To calculate the quantities on which the study is based, we use a Hamiltonian of interacting spins with two magnetic sublattices treated by the HPZ model, a modified Heisenberg Hamiltonian, in which each ionic spin is subject to a local anisotropy field of random orientation. The amorphous alloys studied present ferrimagnetic phase transitions, explained by the magnetic matrix composed of Er and Fe atoms. As a consequence, depending on the Fe doping, compensation temperatures, and inverse magnetocaloric effects are observed. Considerable values of refrigerant capacity in units of J kg${}^{-1}$ under the variation of 5 $T$ of the applied magnetic field were found: 364, 380, 349, 291, and 237 for $x=8.5,10,16.5,21.5$ and 28, respectively.