Experimental and theoretical insights into the structural, magnetic, and low-temperature magnetocaloric properties of RE2CoTiO6 (RE = Gd, Dy, and Er) double perovskite oxides

Herein, a systematic investigation on the structural and magnetic properties, especially the low-temperature magnetocaloric effect (MCE) and magnetocaloric performances, of RE2CoTiO6 (RE = Gd, Dy, and Er) oxides was conducted experimentally and theoretically. All the RE2CoTiO6 oxides crystallized in the monoclinic B-site ordered (P121/n1 space group) double perovskite (DP)-type structure. The magnetic ground state was verified to be antiferromagnetic couplings for all the RE2CoTiO6 DP oxides by first-principles calculations and magnetization measurements. The magnetic transition temperature was determined to be 2.06, 6.05 and 5.99 K for Gd2CoTiO6, Dy2CoTiO6 and Er2CoTiO6, respectively. Large low-temperature MCEs and promising magnetocaloric performances were realized in these RE2CoTiO6 DP oxides. The deduced magnetocaloric parameters of the maximum magnetic entropy change, temperature-averaged magnetic entropy change, relative cooling power and refrigerant capacity of these RE2CoTiO6 DP oxides, especially for Gd2CoTiO6, were at a high level similar to or better than those of the updated magnetocaloric materials, making them of interest for low-temperature magnetic cooling.