Correlation effect in Sr${}_{1-x}$La${}_x$RuO${}_3$ studied by soft x-ray photoemission spectroscopy

Abstract

To clarify how the electronic state of Sr1-xLaxRuO3 evolves with La doping, we conducted photoemission (PES) experiments using soft x-rays. The spectral shape of the Ru 4d derived peak near the Fermi level changes significantly with increasing x. This variation indicates that a spectral weight transfer from the coherent to incoherent component occurs due to an enhancement of the electron correlation effect. Resonant PES experiments at the La 3d_{5/2} edge have confirmed that there is no significant contribution of the La 5d state in the energy range where the spectral weight transfer is observed. Using the dependence of the photoelectron mean free path on the photon energy, we subtracted the surface components from the PES spectra and confirmed that the enhancement of the electron correlation effect with La doping is an intrinsic bulk phenomenon. On the other hand, a large portion of the coherent component remains at the Fermi level up to x = 0.5, reflecting that the Ru 4d state still has itinerant characteristics. Moreover, we found that the PES spectra hardly depend on the temperature and do not exhibit a discernible change with magnetic ordering, suggesting that the temperature variation of the exchange splitting does not follow the prediction of the Stoner theory. The presently obtained experimental results indicate that the electron correlation effect plays an important role in Sr1-xLaxRuO3 and that the Ru 4d electrons possess both local and itinerant characteristics.

8 pages, 4 figures, to be published in Phys. Rev. B

References in corpus (7)

• Dependence of electronic structure of SrRuO3 and the degree of correlation on cation off-stoichiometry
• Quasiparticle Mass Enhancement and Temperature Dependence of the Electronic Structure of Ferromagnetic SrRuO3 Thin Films
• Electronic correlations, magnetism and Hund's rule coupling in the ruthenium perovskites SrRuO${}_3$ and CaRuO${}_3$
• Role of covalency in the ground state properties of perovskite ruthenates: A first principle study using local spin density approximations
• Soft x-ray magnetic circular dichroism study of Ca_1-xSr_xRuO_3 across the ferromagnetic quantum phase transition
• Structural and physical properties of $SrM{n}_{1-x}R{u}_x{O}_3$ perovskites
• Antiferromagnetic Order in Disorder-Induced Insulating Phase of SrRu_{1-x}Mn_xO_3 (0.4<x<0.6)

Cited by in corpus (1)

• Avoided quantum criticality and cluster-glass formation in itinerant ferromagnet Sr${}_{1-x}$(La${}_{0.5}$K${}_{0.5}$)${}_x$RuO${}_3$