Electronic structure trends in the Srn+1RunO

Abstract

The identification of electronic states and the analysis of their evolution with n is key to understanding n-layered ruthenates. To this end, we combine polarization-dependent O 1s x-ray absorption spectroscopy, high-purity Sr n+1 Ru n O 3n+1 (n = 1,2,3) single crystals, and ab initio and many-body calculations. We find that the energy splitting between the empty x 2 − y 2 and 3z 2 − 1 state is considerably smaller than previously suggested and that, remarkably, Sr bands are essential to understanding the spectra. At low energy, we identify the main difference among the materials with a substantial rearrangement of t 2g orbital occupations with increasing n. This rearrangement is controlled by the interplay of Coulomb repulsion, dimensionality, and changes in the t 2g crystal field.

Spin-orbit-induced orbital excitations inSr2RuO4andCa2RuO4: A resonant inelastic x-ray sc

“…1 and 2, x-ray absorption spectra recorded on Ca 2 RuO 4 and Sr 2 RuO 4 are shown for different light polarizations and incident angles θ . Good agreement with previous XAS work [17,18] is found whenever overlap in temperature, polarization, and incident angle is present. As generally observed on cuprates [28], iridates [23], and ruthenates [17,18], the t 2g and e g states can be probed through oxygen hybridization on both the apical and planar oxygen sites, which have slightly different absorption resonance energies [28].…”

“…The first two features in Figs to Ru t 2g hybridization with apical and planar oxygen, respectively [17,18]. Features at higher energies are attributed to hybridization with e g (d 3z 2 −r 2 and d x 2 −y 2 ) Ru orbitals [17].…”

“…Current experimental evidence for a strong spinorbit interaction stems from absorption spectroscopy [17][18][19], which has revealed a considerable admixture of the ruthenium t 2g orbitals. More recently, spin-resolved photoemission spectroscopy has reported spin-polarized bands in Sr 2 RuO 4 [20,21].…”

Double metamagnetic transition inSr4Ru3O10

“…There is in fact no doubt that the stabilization of metamagnetism in the framework of the multiorbital character of the Ru bands is coupled with the lattice distortions as well as the evolution of the lattice parameters with both temperature and pressure. The in-plane rotations of the octahedra described above affect the site-specific local DOS and bandwidth in a different way [40], as predicted by ab initio calculations based on the local density approximation (LDA) [41]. In this paper it was reported that both the Ru t 2g crystal-field splitting = E zx/yz − E xy (and, as a consequence, the total orbital polarization calculated from LDA) is positive in the inner layer and negative in the two outer ones.…”

Multiorbital physics in Fermi liquids prone to magnetic order

“…Figure 3 shows the t 2g -like QP band structure of Sr 2 RuO 4 from the extended-LDA treatment. One observes the expected combined main features already known from the existing separate SOC 28,30,32 and correlated 26,29,31,47 studies, namely the lifting of degeneracies, e.g., close to the point for the bands with dominant xz,yz character, also resulting in now avoided band crossings, e.g., close to the X point, when including SOC. Electronic correlations lead in the present approximation to band-narrowing and -shifting.…”