Bulk magnetic characterization of RCaCrO4 (R  Y, Pr, Sm) oxides

Abstract

The system RCaCrO4 (R  Y, Sm, Pr) presents an orthorhombic structure (space group Bmab) at room temperature (RT), similar to that observed in La2MO4 (M  Cu, Ni, Co). The magnetic susceptibility for RCaCrO4 shows a weak temperature dependence down to 250 K, probably due to the antiferromagnetic ordering of the Cr sublattice above RT. Below RT there is a strong upturn anomaly at 210, 190 and 130 K for Pr, Sm and Y, respectively. This anomaly is associated with the appearance of a weak ferromagnetic component, and could be related to a low temperature structural phase transition, similar to that observed in the related compounds R2NiO4 or La1.88Ba0.12CuO4. In the case of YCaCrO4 this ferromagnetic component produces a hysteresis curve at 4.5 K with a coercive field of 0.7 T. For PrCaCrO4 the coercive field is very small (< 0.05 T). SmCaCrO4 shows a more complicated behavior with a low temperature magnetic transition (TN2 ≈ 40 K), which could be associated with either the antiferromagnetic ordering of the Sm sublattice or a spin reorientation in the Cr sublattice.