A comparative investigation on structural, magnetic and magnetocaloric properties of Tb2MTiO6 (M = Co, Ni, Cu) compounds

The structure, magnetic behavior and magnetocaloric performance in heavy rare–earth based compounds Tb 2 M TiO 6 ( M  = Co, Ni, Cu) have been experimentally investigated in this work. The structural analysis indicates that Tb 2 CoTiO 6 and Tb 2 NiTiO 6 crystallize in a monoclinic double perovskite structure, while Tb 2 CuTiO 6 forms a hexagonal layered structure. The magnetic measurements reveal that the samples show high magnetic reversibility within a wide temperature range. The high-temperature Curie–Weiss fitting suggests that the antiferromagnetic coupling between RE 3+   and RE 3+ is dominant at low temperatures. The Arrott-plots imply that the magnetic transition in Tb 2 M TiO 6 is of second–order nature according to the Banerjee’s criteria. The magnetic entropy change − Δ S M is evaluated to be 10.7, 16.2 and 13.2 J kg −1  K −1 for Tb 2 CoTiO 6 , Tb 2 NiTiO 6 and Tb 2 CuTiO 6 at 4 K and magnetic field change Δ H  = 6 T, respectively. The work suggests that the lack of 3 d –3 d coupling in the design of double perovskites is one of the potential approaches for developing low-temperature magnetic refrigeration materials.