Evidence for strong electronic correlations in the spectra ofSr2RuO4

Abstract

The importance of electronic correlation effects in the layered perovskite Sr2RuO4 is evidenced. To this end we use state-of-the-art LDA+DMFT (Local Density Approximation + Dynamical MeanField Theory) in the basis of Wannier functions to compute spectral functions and the quasiparticle dispersion of Sr2RuO4. The spectra are found to be in good agreement with various spectroscopic experiments. We also calculate the k-dependence of the quasiparticle bands and compare the results with new angle resolved photoemission (ARPES) data. Two typical manifestations of strong Coulomb correlations are revealed: (i) the calculated quasiparticle mass enhancement of m * /m ≈ 2.5 agrees with various experimental results, and (ii) the satellite structure at about 3 eV binding energy observed in photoemission experiments is shown to be the lower Hubbard band. For these reasons Sr2RuO4 is identified as a strongly correlated 4d electron material.

Electronic structure trends in the Srn+1RunOMalvestuto1, Carleschi2, Fittipaldi3 et al. 2011Phys. Rev. B367400View full textAdd to dashboardCite

“…We take as parameters U = 3.1 eV and J = 0.7 eV, in line with theoretical estimates. 2,36 We find that p is somewhat smaller than in the LDA: At 290 K, p DMFT ∼ −0.11 for Sr 2 RuO 4 and p DMFT ∼ 0 for Sr 3 Ru 2 O 7 . Thus, due to many-body effects, holes are partially transferred from the xy bands to the xz and yz bands; 16 however, down to 290 K the trend remains the same as in the LDA.…”

Mott transition, spin-orbit effects, and magnetism in Ca2RuO4

“…The main differences between the two results are (i) the size of the gap (slightly smaller for the cRPA values) and (ii) the shape of the lower Hubbard band. Both spectral functions exhibit Hubbard bands more or less in line with the spectra measured in photoemission, x-ray fluorescence emission, and x-ray absorption spectroscopy experiments [41,[43][44][45], thus it is difficult, based on experiments available so far, to decide conclusively in favor of one set or the other. For this reason we will present, when necessary, results for both the cLDA and cRPA parameter sets.…”

“…The first, U = 3.1 eV and J = 0.7 eV, has been obtained for Sr 2 RuO 4 , the sister compound of Ca 2 RuO 4 , via the constrained local-density approximation (cLDA) [41]. These parameters have been already successfully used [23] to describe the metal-insulator transition in Ca 2 RuO 4 with the LDA+DMFT approach.…”

Subband Filling and Mott Transition inCa2−xSrxRuO4

“…In reality, U should be roughly constant as a function of x, with U ≈ 3.1 eV and J ≈ 0.7 eV according to constrained LDA calculations for x = 2 [11]. Thus, in Fig.…”