New ferrimagnetic oxide CaCu3Cr2Sb2O12:: High-pressure synthesis, structure, and magnetic properties

A new perovskite-type oxide, CaCu3Cr2Sb2O12, has been synthesized at 10 GPa and 1100 degrees C. This compound crystallizes in space group Pn (3) over bar and shows simultaneous cation ordering on both A and B sites. Magnetization measurements indicate that an interaction between A-site Cu(II) and B-site Cr(III) cations dominates over possible antiferromagnetic couplings between Cu(II)-Cu(II) ions or Cr(III)Cr(III) ions and induces net spontaneous magnetic moment below similar to 160 K. The lack of significant hysteresis in the isothermal magnetization curves suggests that CaCu3Cr2Sb2O12 is a soft ferrimagnet, which is consistent with the thermomagnetic irreversibility and magnetic susceptibility behavior. Interestingly, the experimentally determined effective magnetic moment of similar to 1.4 mu B at 5 K is significantly smaller than the expected value of 3 mu(B) estimated assuming an antiparallel alignment of the spins of Cu(II) and Cr(III). Significant spin canting may account for the small magnetic moment. Such an anomalously small magnetization is similar to that of CuCr2O4 spinel showing a non-unidirectional spin canting behavior.