Cation order control of correlations in double perovskite Sr2VNbO6

Arpita Paul,Turan Birol

doi:10.1103/physrevresearch.2.033156

Abstract

Double perovskites extend the design space for new materials, and they often host phenomena that don't exist in their parent perovskite compounds. Here, we present a detailed first principles study of the correlated double perovskite Sr$_2$VNbO$_6$, where inter-cationic charge transfer and strength of electronic correlations depend strongly on the cation order. By using Density Functional Theory + Embedded Dynamical Mean Field Theory, we show that this compound has a completely different electronic structure than either of its parent compounds despite V and Nb being from the same group in the periodic table. We explain how the electronic correlations' effect on the crystal structural parameters determines on which side of the Hund's metal-Mott insulator transition the material is. Our results demonstrate the emergence of Hund's metallic behavior in a double perovskite that has $d^1$ parents, and underlines the importance of electronic correlation effects on the crystal structure.

Highlights

Transition metal oxides (TMOs) are the focus of great interest as they host a wide variety of electronic phenomena including metal-insulator transitions, charge orbital, or spin ordering, multiferroicity, colossal magnetoresistance, different types of magnetism, and high-temperature superconductivity [1,2,3,4]
In order to elucidate the origin of strong correlations in double perovskite Sr2VNbO6, we repeat our DFT+eDMFT calculations using the same value of Hubbard U, but varying the value of Hund’s coupling J. (Our results so far used J = 0.7 eV, a typical value for V in our implementation.) The results presented in Fig. 2(b) show that both Z and α strongly depend on J
Even though V and Nb are both group 5 transition metals, there is almost complete charge transfer between them when they coexist in the double perovskite

Summary

Introduction

Transition metal oxides (TMOs) are the focus of great interest as they host a wide variety of electronic phenomena including metal-insulator transitions, charge orbital, or spin ordering, multiferroicity, colossal magnetoresistance, different types of magnetism, and high-temperature superconductivity [1,2,3,4]. Many of these emergent properties and rich phase diagrams arise from the interplay between charge, spin, orbital, and lattice degrees of freedom. Multiple B-site transition metal cations provide one more degree of freedom to realize different electronic phases such as the rare combination of ferromagnetism with insulating behavior that is rather commonplace in double

Methods

Results

Conclusion