Anisotropic properties, charge ordering, and ferrimagnetic structures in the strongly correlated β- V2PO5 single crystal

Single crystal β-V2PO5 was synthesized by chemical vapor transport method and characterized by transport, thermodynamic, neutron diffraction, nuclear magnetic resonance measurements and first-principles calculation. It was shown to be a semiconductor with a band gap of 0.48 eV, undergoing a charge ordering (unusual V2+ and V3+) phase transition accompanied by a tetragonal to monoclinic structural distortion at 610 K and a paramagnetic to ferrimagnetic phase transition at 128 K with a propagation vector of k=0. The easy axis is in the monoclinic ac plane pointing 47(9)∘ away from the monoclinic a axis. This collinear ferrimagnetic structure and anisotropic isothermal magnetization measurements suggest weak magnetic anisotropy in this compound. The first-principles calculations indicate that the intrachain interactions in the face-sharing VO6 chains dominate the magnetic hamiltonian and identify the Γ5+ normal mode of the lattice vibration to be responsible for the charge ordering and thus the structural phase transition.