Enroute To Phase Purity In CaMn7O12

We present structural, magnetic and X-ray absorption spectroscopy investigations on multiferroic CaMn7O12 material. Traces of impurities (viz CaMn2O4, Mn3O4, and Mn2O3) are reported to be inevitable in this compound [J. Phys: Condense Matter 14, 5747 (2002)]. We have shown that the synthesis temperature plays a significant role in phase control of this compound. Samples, synthesized using two different temperatures are studied. X-ray absorption spectra measured across Mn L3, 2 edges of both the samples show the mixed valence states of Mn (Mn3+ and Mn4+), and increasing Mn4+ content for sample sintered at elevated temperature, which supports the stabilization of pure CaMn7O12 phase, also confirmed from XRD. Both the samples show reported antiferromagnetic transitions, T-NI similar to 90 K and T-N2 similar to 45 K, however, with different magnetic anisotropies at lower temperatures.