Enhanced Cryogenic Magnetocaloric Effect from 4f-3d Exchange Interaction in B-Site Ordered Gd2CuTiO6 Double Perovskite Oxide

Magnetic refrigeration based on the principle of the magnetocaloric effect (MCE) in magnetic solids has been considered as a prospective cooling technology. Exploring suitable magnetocaloric materials (MCMs) is a vital prerequisite for practical applications. Herein, an excellent cryogenic MCM-the B-site-ordered Gd2CuTiO6 double perovskite (DP) oxide-which exhibits the largest MCE among known Gd-based DP oxides, is identified. Such enhanced cryogenic MCE in the Gd2CuTiO6 DP oxide likely stems from the exchange interaction effect between Gd-4f and Cu-3d magnetic sublattices. Under a magnetic field change of 0-7 T, the maximum magnetic entropy change (-Delta STmax) of the Gd2CuTiO6 DP oxide reaches 51.4 J kg(-1) K-1 (378.2 mJ cm(-3) K-1), which is much larger than that of the commercialized magnetic refrigerant Gd(3)Ga5O(12), which is 38.3 J kg(-1 )K(-1) (271.2 mJ cm(-3 )K(-1)), and it is also superior to most of the recently reported benchmarked cryogenic MCMs, indicating the possibility for practical applications. This work also provides a productive route for future cryogenic MCM design by harnessing 4f-3d exchange interactions.