3d-4f spin interaction and field-induced metamagnetism in RCrO4 (R = Ho, Gd, Lu) compounds

We observe that the zircon-type RCrO4 (R = Ho, Gd, Lu) compounds exhibit complicated magnetic properties and large magnetic entropy change due to the strong competition between ferromagnetic and antiferromagnetic interactions. For a field change of 7 T, the maximum values of entropy change and refrigerant capacity reach 28 J kg−1 K−1 and 740 J kg−1, respectively, for GdCrO4 whereas the corresponding values for HoCrO4 are 29 J kg−1 K−1 and 550 J kg−1. For GdCrO4 compound, the magnetic entropy change is quite large even at low temperatures well below the ferromagnetic transition.