A detailed first-principles study of the α phase of copper pyrovanadate is carried out to understand the magnetic and multiferroic properties of this material. The crystal geometry of the material is found to have a crucial impact on the magnetic interactions of the material. The relevant spin Hamiltonian derived from the calculated isotropic exchange interactions is found to be three-dimensional. In addition to the isotropic interactions, the asymmetric Dzyaloshinski-Moriya (DM) interaction, driven by spin-orbit coupling (SOC) in absence of inversion symmetry, is also found to be appreciable resulting in the canting of the Cu-spins. The magnetism in the material is closely related to the ferro-orbital ordering driven by the polar distortion of the CuO5 pyramids. The predicted magnetic ground state of the system from the structures allowed by symmetry, is in agreement with the experimental observations. The calculation of the ferroelectric polarization in the symmetry allowed magnetic structures indicate that the giant ferroelectric polarization observed in the system is primarily driven by the symmetric exchange-striction mechanism and is corroborated by temperature-dependent X-ray studies.
At the request of all authors of the paper, an updated version of this article was published on 22 August 2018. The original article supplied to AIP Publishing was found to have missing information in Figure 2. In the Y axes in Fig. 2 (a) and (b) the letter 'V' was excluded and in the label of X axes in Fig. 2(b) the letters Z and X are missing. These errors have been corrected in the updated and re-published article.