Ground State Properties and Optical Conductivity of the Transition Metal Oxide $\mathrm{S}{\mathrm{r}}_2\mathrm{V}{\mathrm{O}}_4$

Abstract

Combining first-principles calculations with a technique for many-body problems, we investigate properties of the transition metal oxide $\mathrm{S}{\mathrm{r}}_2\mathrm{V}{\mathrm{O}}_4$ from the microscopic point of view. By using the local density approximation (LDA), the high-energy band structure is obtained, while screened Coulomb interactions are derived from the constrained LDA and the GW method. The renormalization of the kinetic energy is determined from the GW method. By these downfolding procedures, an effective Hamiltonian at low energies is derived. Applying the path integral renormalization group method to this Hamiltonian, we obtain ground state properties such as the magnetic and orbital orders. Obtained results are consistent with experiments within available data. We find that $\mathrm{S}{\mathrm{r}}_2\mathrm{V}{\mathrm{O}}_4$ is close to the metal-insulator transition. Furthermore, because of the coexistence and competition of ferromagnetic and antiferromgnetic exchange interactions in this system, an antiferromagnetic and orbital-ordered state with a nontrivial and large unit cell structure is predicted in the ground state. The calculated optical conductivity shows characteristic shoulder structure in agreement with the experimental results. This suggests an orbital selective reduction of the Mott gap.

38pages, 22figures

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• Ab-initio Low-Energy Model of Transition-Metal-Oxide Heterostructure LaAlO3/SrTiO3
• Optical Absorption Study by Ab initio Downfolding Approach: Application to GaAs
• Competing magnetic interactions in spin-1/2 square lattice: hidden order in Sr${}_2$VO${}_4$
• Effective interaction for vanadium oxyhydrides Sr${}_{n+1}$V${}_n$O${}_{2n+1}$H${}_n$ ($n=1$ and $n\to \infty$): A constrained-RPA study