Universality class change from Mean-Field to 3D-Heisenberg in magnetocaloric compounds [formula omitted][formula omitted

Abstract

We report a study of universality class change from Mean-Field to 3D-Heisenberg in magnetocaloric compounds SmNi3-xFex. Three conventional techniques are used to identify the universal classes: the Modified Arrott plot, Kouvel-Fisher plot, and critical isotherm technique. The calculated critical exponents were confirmed and the isotherm M(H) curves in paramagnetic state and ferromagnetic state fall in two separated universal branches. The exponents found are similar to those determined from the renormalization group approach for a heuristic mean-field (d=3,n=3) and 3D-Heisenberg (d=3,n=3) model for SmNi3 and SmNi2.2Fe0.8, respectively.