Designing gadolinium-transition metals-based perovskite type high entropy oxides with good cryogenic magnetocaloric performances

Cryogenic magnetic cooling based on the principle of the magnetocaloric effects (MCEs) of magnetic solids has been recognized as an alternative cooling technology due to its significant economic and social benefits. Designing novel magnetic materials with good magnetocaloric performance is a prerequisite for practical applications. In this study, three gadolinium-transition metal-based high entropy oxides (HEOs) of Gd(Fe1/4Ni1/4Al1/4Cr1/4)O3, Gd(Fe1/5Ni1/5Al1/5Cr1/5Co1/5)O3, and Gd(Fe1/6Ni1/6Al1/6Cr1/6Co1/6Mn1/6)O3 were designed and systematically characterized regarding their structural and cryogenic magnetic properties. These HEOs were confirmed to crystallize into a single-phase perovskite-type orthorhombic structure with a homogeneous microstructure, reveal a second-order magnetic transition at low temperatures, and exhibit significant cryogenic MCEs. The magnetocaloric performances of the present HEOs, identified by magnetic entropy changes, relative cooling power, and temperature-averaged entropy changes, were comparable with recently reported candidate materials. The present study indicates potential applications for cryogenic magnetic cooling of the present HEOs and provides meaningful clues for designing and exploring HEOs with good cryogenic magnetocaloric performances.