Abstract: The magnetic functional materials play a particularly important role in our modern society and daily life. The magnetocaloric effect (MCE) is at the basis of a solid state magnetic refrigeration (MR) technology which may enhance the efficiency of cooling systems, both for room temperature and cryogenic applications. Despite numerous experimental and theoretical MCE studies, commercial MR systems are still at developing stage. Designing magnetic solids with outstanding magnetocaloric performances remains therefore a most urgent task. Herein, recent progresses on characterizing the crystal structure, magnetic properties and cryogenic MCE of rare earths (RE)-based RE₂TMTM'O₆ double perovskite (DP) oxides, where TM and TM' are different 3d transition metals, are summarized. Some Gd-based DP oxides are found to exhibit promising cryogenic magnetocaloric performances which make them attractive for active MR applications.

Key words: Magnetocaloric effect (MCE), Rare earths, Double perovskite (DP) oxides, Magnetic functional materials, Cryogenic magnetic refrigeration, Magnetocaloric performances