Spin-Glass Behavior and Incommensurate Modulation in High-Pressure Perovskite BiCr sub(0.5)Ni sub(0.5)O sub(3)

The BiCr sub(0.5)Ni sub(0.5)O sub(3) perovskite has been obtained at high pressure. Neutron and synchrotron diffraction data showa Pnma orthorhombic structure with a = 5.5947(1) [Angstrom], b = 7.7613(1) [Angstrom], and c = 5.3882(1) [Angstrom] at 300 K and random B-site Cr/Ni distribution. Electron diffraction reveals an incommensurate modulation parallel to the b axis. The combination of either Cr-O-Ni (J > 0) or Cr-O-Cr/Ni-O-Ni (J < 0) nearest-neighbor spin interactions results in a random-bond spin-glass configuration. Magnetization, neutron diffraction, and muon-spin-relaxation measurements demonstrate that variations in the local bonding and charge states contribute to the magnetic frustration.