Nonlocal Interactions in the Double Perovskite Sr2FeMoO6 from Core-Level X-ray Spectroscopy

Dibya Phuyal,Gabriel J Man,Soham Mukherjee,Swarup K Panda,Sergei M Butorin,Håkan Rensmo,Konstantin Simonov,Olof Karis,Laura Simonelli

doi:10.1021/acs.jpcc.1c02580

Abstract

The valence electronic structure of the half-metallic double perovskite Sr2FeMoO6 forms from a strongly hybridized band in the spin-down channel of Fe 3d and Mo 4d states that provides metallic conductivity and a gapped spin-up channel. The ground-state description has previously been explored in terms of many-body interactions where local and nonlocal interactions produce states with a combination of a charge-transfer configuration and intersite charge fluctuations. Here, we provide a qualitative understanding on nonlocal effects in Sr2FeMoO6 using a combination of core-level X-ray spectroscopies, specifically X-ray absorption, emission, and photoelectron spectroscopies. Our spectroscopic data indicate intersite Fe 4p–O 2p–Mo 4d interactions to be the origin of these nonlocalized transitions. Close to the Fermi level, this interaction is dominated by Mo 4d–O 2p character. When our data are compared against first-principles electronic structure calculations, we conclude that a full understanding of the nature of these states requires a spin-resolved description of the hybridization functions and that the nonlocal screening occurs predominantly through hybridization in the minority spin channel of the Mo 4d bands.

Highlights

Double perovskite (DP) oxides offer a unique material framework to engineer a wide range of physics with a multitude of functionalities
In its simplest form, the DP structure (A2BB′O6) consists of two transition metal (TM) ions interspersed by corner-sharing octahedra that can be arranged in a rock-salt, layered, or columnar order.[1]
The inset shows the relative variation of determined magnetic moment and integral absolute difference (IAD) values plotted as a function of references and SFMO, where qualitatively similar trends are observed

Summary

■ INTRODUCTION

Double perovskite (DP) oxides offer a unique material framework to engineer a wide range of physics with a multitude of functionalities. The choice of the B/ B′ cations can profoundly alter a material’s electronic structure, creating materials with desired functionalities ranging from spin-polarized metals to strongly correlated systems, spin− orbit effects, ferroelectricity, and complex magnetic properties, to name a few examples.[2−7]. Exchange interaction results between Fe localized moments and conduction electrons This relationship of interatomic electronic and magnetic structures and competition between electron localization and hybridization are relevant ingredients in determining a material’s Curie temperature and ferromagnetic state.[15] This nonlocal interaction between every other Fe site produces interesting coupling schemes that constitute the basis of this study and relevant to other magnetic perovskite oxides. In a quantum impurity model, Δ(E) gives the properties of the bath surrounding the impurity cluster and describes the interaction of an impurity electron (in our case, d-electrons of either Fe or Mo ions) with the bath consisting of all other electrons

■ RESULTS AND DISCUSSION

■ CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES