Bulk-sensitive photoemission spectroscopy of A_2FeMoO_6 double perovskites (A=Sr, Ba)

TL;DR

This study uses bulk-sensitive photoemission spectroscopy to analyze the electronic structures of Sr2FeMoO6 and Ba2FeMoO6 double perovskites, revealing mixed-valence states and strong Mo-Fe hybridization near the Fermi level.

Contribution

It provides detailed experimental insights into the electronic structure and valence states of A2FeMoO6 double perovskites, highlighting mixed-valence and hybridization effects.

Findings

Mo-Fe t2g states are strongly mixed near the Fermi level.

Fe valence is mixed, with Fe^{3+} and Fe^{2+} components.

Ba2FeMoO6 shows a larger Fe^{2+} component than Sr2FeMoO6.

Abstract

Electronic structures of Sr_2FeMoO_6 (SFMO) and Ba_2FeMoO_6 (BFMO) double perovskites have been investigated using the Fe 2p->3d resonant photoemission spectroscopy (PES) and the Cooper minimum in the Mo 4d photoionization cross section. The states close to the Fermi level are found to have strongly mixed Mo-Fe t_{2g} character, suggesting that the Fe valence is far from pure 3+. The Fe 2p_{3/2} XAS spectra indicate the mixed-valent Fe^{3+}-Fe^{2+} configurations, and the larger Fe^{2+} component for BFMO than for SFMO, suggesting a kind of double exchange interaction. The valence-band PES spectra reveal good agreement with the LSDA+U calculation.