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

• Published in: Journal of applied physics 2024-03, Vol.135 (12)
• Main Authors: Kumar, G. Jagadish, Guo, Zengli, Gu, Lisha, Feng, Jinliang, Kamala Bharathi, K., Wang, Ke
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Compensation; Entropy; Gadolinium; Magnetic measurement; Refrigeration; Regenerators; Room temperature; Temperature; Temperature dependence; Thickness; Thin films; Transition metals
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/5.0191497

We demonstrate magnetocaloric entropy change and compensation temperatures in ferrimagnetic Gdx(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 Gdx(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 (ΔH = ± 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.