title: First-principles investigation of exchange interactions in quasi-one-dimensional antiferromagnet CaV2O4.
abstract: The effects of orbital degrees of freedom on the exchange interactions in a quasi-one-dimensional spin-1 antiferromagnet CaV2O4 are systematically studied. For this purpose a realistic low-energy electron model with the parameters derived from the first-principles calculations is constructed in the Wannier basis for the t2g bands. The exchange interactions are calculated using both the theory of infinitesimal spin rotations near the mean-field ground state and the superexchange model, which provide a consistent description. The obtained behaviour of exchange interactions differs substantially from the previously proposed phenomenological picture based on magnetic measurements and structural considerations, namely: (i) despite the quasi-one-dimensional character of the crystal structure, consisting of the zigzag chains of the edge-sharing VO6 octahedra, the electronic structure is essentially three-dimensional, that leads to finite interactions between the chains; (ii) the exchange interactions along the legs of the chains appear to dominate; and (iii) there is a substantial difference in exchange interactions in two crystallographically inequivalent chains. The combination of these three factors successfully reproduces the behaviour of experimental magnetic susceptibility.
authors.affiliation: M N Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620137, Ekaterinburg, Russia. Theoretical Physics and Applied Mathematics Department, Institute of Physics and Technology, Ural Federal University, Ekaterinburg 620002, Russia.
authors.forename: Z V
authors.initials: ZV
authors.lastname: Pchelkina
authors.forename: I V
authors.initials: IV
authors.lastname: Solovyev