Charge Disproportionation and Complex Magnetism in a PbMnO3Perovskite Synthesized under High Pressure

Because of the possible crossover of Pb and 3d transition-metal (TM) redox levels, a charge transfer between Pb and TMleads to a continuous evolution from Pb2+Ti4+O3to Pb4+Ni2+O3in the perovskite family of PbTMO3as verified by several reports. However, very little information is known about PbMnO3in the PbTMO3series. The perovskite PbMnO3is the most difficult one to synthesize, although its geometric tolerance factor is close to 1. Here, we report a careful study of PbMnO3synthesized under 15 GPa by a structural refinement and high-precision X-ray absorption spectroscopy (XAS) as well as a variety of measurements of physical properties. We can rationalize the physical properties of PbMnO3based on a local bonding model and the valence states of Pb and Mn from XAS. Moreover, the complete study of PbMnO3allows us to construct a more consistent picture of the valence evolution and the charge disproportionation for the entire family of PbTMO3perovskites.