Manipulation of magnetocaloric effect in FeRh films by epitaxial growth

Abstract

In this study, the growth mechanism and its influence on the phase transition and magnetocaloric effect of FeRh films grown on MgO, LaAlO3, SrTiO3, and PMN-PT substrates were studied. The results demonstrate that different growth mechanisms are possessed in these FeRh films, although the orientation and lattice parameter are similar for these substrates. Thus, various strains and local disorder are generated in FeRh films, resulting in manipulation of the phase transition and magnetocaloric effect within them. The transition temperatures of FeRh films are tuned from 342.5 K to 382.5 K by changing substrates, whereas their entropy changes (ΔS) are comparable with that of the bulk FeRh. As a result, regulated entropy changes and refrigeration capacity in a wide temperature span have been achieved, reaching 80 (65) K with ΔS exceeding 6 (10) J/kgK. This study provides direct experimental evidence for the feasibility of broadening the working temperature span of first-order phase transition materials via epitaxial growth, exhibiting their potential in microelectronic circuitry.