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.
Bibliographical noteFunding Information:
Work at UCLA (J.X., C.W.H., R.C., N.N.) was supported by NSF DMREF program under the award NSF DMREF project DMREF-1629457. Work at ORNL HFIR was sponsored by the Scientific User Facilities Division, Office of Science, Basic Energy Sciences, U.S. Department of Energy. Work at UMN was supported by NSF DMREF program under the award NSF DMREF project DMREF-1629260. Work at UCLA (H.H.W., Y.K.L., S.B.) was supported by NSF DMR-1410343 and DMR-1709304. Y.K.L. would also like to thank the support from LANL LDRD program.