Many-body effects and non-local charge fluctuations in the double perovskite Sr₂FeMoO₆

Abstract

We studied the electronic structure of Sr2FeMoO6 using core level and valence band photoemission.

Role of Ti-Ru interaction in SrTi0.5Ru0.5O3 : Physical properties, x-ray spectroscopy, and cluster model calculations

“…As a comparison, a different behavior of the screening mechanisms in the core-level and valence-band spectra was also observed in a double cluster model study on Sr 2 FeMoO 6 . While in the valence-band spectrum there is a clear signature of Fe-Mo nonlocal screening, the character of the Fe 2p and Mo 3p core-level peaks is similar to the ones obtained by single cluster model calculations [42], indicating that the interplay between two different TMO 6 octahedra depend on the ZSA [40] classification of each system.…”

“…The reason for the differences may stem from the fact that both Ti 4+ and Ru 4+ ions favor the sharing of an O 2p electron, or in other words, the GS of the double perovskite is governed by charge-transfer configurations to such an extent that further ligand screening is not favorable. In a recent double cluster model calculation of Sr 2 FeMoO 6 [42], it was shown that the character of the Fe 2p and Mo 3p core-level peaks are mostly the same regardless of being calculated with double or single cluster models. In such a system, the Fe 3+ and Mo 5+ ions are classified within the chargetransfer ( < U ) and Mott-Hubbard ( > U ) regimes, respectively.…”

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

“…From previously reported double cluster calculations on SFMO, 20 the ground state was reported to be described by a mixed character of ionic 3d 5 as well as locally screened 3d 6 L and nonlocal 3d 6 v configurations, where v represent a hole in the valence band. The nonlocal screening involves an oxygen mediated Fe 3d−O 2p−Mo 4d hybridization.…”

“…16−18 The complete ground-state electronic structure description in SFMO presents a more complex picture due to the large Fe−O and Mo−O hybridization as well as the importance of nonlocal Fe−O− Mo charge fluctuations. 19,20 This intricacy arises from the antiferromagnetic coupling between Fe and Mo sites, e.g., unlike the ferromagnetic coupling in manganites. In contrast to manganites like La 1−x Sr x MnO 3 , the strong local coupling in SFMO only applies to every other site since Mo is paramagnetic.…”

“…One of the most studied materials in this class is the half-metallic and ferrimagnetic Sr 2 FeMoO 6 (henceforth termed SFMO) . It is known to have a purely spin-polarized band structure where only one-spin direction is present at the Fermi level. − The large room-temperature magnetoresistance is noteworthy for its potential use in spintronic devices based on the high spin polarization of charge carriers. ,− In the ionic picture, the electronic structure is understood to have a Fe 3+ (3d 5 ) sites as localized with a high-spin S = 5/2 configuration together with Mo 5+ (4d 1 ) sites with one conduction electron that can hop between Mo and Fe sites in the exchange split t 2g orbitals. − The complete ground-state electronic structure description in SFMO presents a more complex picture due to the large Fe–O and Mo–O hybridization as well as the importance of nonlocal Fe–O–Mo charge fluctuations. , This intricacy arises from the antiferromagnetic coupling between Fe and Mo sites, e.g., unlike the ferromagnetic coupling in manganites. In contrast to manganites like La 1– x Sr x MnO 3 , the strong local coupling in SFMO only applies to every other site since Mo is paramagnetic .…”