Ground State Properties and Optical Conductivity of the Transition Metal Oxide ${\rm Sr_{2}VO_{4}}$

TL;DR

This study combines first-principles calculations and many-body techniques to analyze the ground state and optical properties of ${\rm Sr_{2}VO_{4}}$, revealing its proximity to a metal-insulator transition and complex magnetic ordering.

Contribution

It introduces a comprehensive approach integrating LDA, GW, and path integral renormalization group methods to accurately predict properties of ${\rm Sr_{2}VO_{4}}$, including magnetic, orbital, and optical characteristics.

Findings

${\rm Sr_{2}VO_{4}}$ is close to the metal-insulator transition.

Predicted antiferromagnetic and orbital-ordered ground state with a large unit cell.

Optical conductivity features match experimental shoulder structures.

Abstract

Combining first-principles calculations with a technique for many-body problems, we investigate properties of the transition metal oxide ${\rm Sr_{2}VO_{4}}$ 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 ${\rm Sr_{2}VO_{4}}$ 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.