Broad table-like magnetocaloric effect in GdFeCo thin-films for room temperature Ericsson-cycle magnetic refrigeration

We demonstrate magnetocaloric entropy change and compensation temperatures in ferrimagnetic Gd-x(Fe10Co90)(100-x) amorphous thin films with transition metal-rich and rare earth-rich configurations. Thin films are sputtered with same Gd/FeCo elemental ratio at different thicknesses and of various Gd/FeCo ratios at a constant thickness to understand the effect of these two parameters on an antiferromagnetically coupled magnetic sub-lattice system. Temperature- and field-dependent magnetic measurements [M(H,T)] and magnetocaloric studies are performed over a broad range of temperature (70-600 K) by applying a magnetic field of +/- 15 kOe on sputter deposited 90 nm thin films of Gd-x(Fe10Co90)(1-x)(x = 30,40,50,55,70). The compensation temperature is found to increase with increasing Gd concentration for thin films of the same thickness. A high magnetocaloric entropy change around 0.97 J/kg K (Delta H = +/- 15 kOe) is observed for thin films having the same Gd/FeCo elemental ratio. Furthermore, we observed a "table-like" magnetocaloric entropy change in GdFeCo thin film stacks with a high operational window (60 K) at a low applied field for an Ericsson magnetic regenerator around room temperature. The studies will provide important insight into magnetocaloric studies for Ericsson-cycle refrigeration in thin films having antiferromagnetically coupled sublattices.