Electronic structure of doped lanthanum cuprates studied with resonant inelastic x-ray scattering

Abstract

We report a comprehensive Cu K-edge RIXS investigation of La2−xSrxCuO4 (LSCO) for 0≤x≤0.35, stripe-ordered La1.875Ba0.125CuO4 (LBCO), and La2Cu0.96Ni0.04O4 (LCNO) crystals. The RIXS spectra measured at three high-symmetry momentum transfer (q) positions are compared as a function of doping and for the different dopants. The spectra in the energy range 1-6 eV can be described with three broad peaks, which evolve systematically with increased doping. The most systematic trend was observed for q=(π, 0) corresponding to the zone boundary. As hole doping increased, the spectral weight transfer from high energies to low energies is nearly linear with x at this q. We interpret the peaks as interband transitions in the context of existing band models for this system, assigning them to Zhang-Rice band→upper Hubbard band, lower-lying band→upper Hubbard band, and lower-lying band→Zhang-Rice band transitions. The spectrum of stripe-ordered LBCO was also measured, and found to be identical to the correspondingly doped LSCO, except for a relative enhancement of the near-infrared peak intensity around 1.5-1.7 eV. The temperature dependence of this near-infrared peak in LBCO was more pronounced than for other parts of the spectrum, continuously decreasing in intensity as the temperature was raised from 25 K to 300 K. Finally, we find that 4% Ni substitution in the Cu site has a similar effect on the spectra as does Sr substitution in the La site.

Bimagnon studies in cuprates with resonant inelastic x-ray scattering at the OKedge. II. Doping effect in La2−xSrx<

“…The present results are fully consistent with the interpretation given in Ref. 13 where the feature is assigned to a transition from d states to a band intersecting the Fermi level and derived from ZR singlets. Note that there is also the counterpart transition with change of parity seen at q = 0 with optical measurements by Uchida et al 14 In the O K edge data, as already noticed, this feature is hardly seen at increasing doping so that we cannot go deeper on this topic.…”

Correlation of the superconducting critical temperature with spin and orbital excitations in(CaxLa1−x)(Ba1.75−Ellis1, Huang2, Olalde-Velasco3 et al. 2015Phys. Rev. B301191View full textAdd to dashboardCite

“…2(b), and the energies are shifted so that the quasielastic peaks in The feature is shifted to higher energy for x = 0.4 and is also present in the doped samples. A doping-independent feature at similar energy was studied in La 2−x Sr x CuO 4 (LSCO) with Cu K-edge RIXS [39]. Figure 2(b) is an overall view of the spectra including both the intense peak encompassing the dd excitations between 1.5 and 1.8 eV and the lower energy peaks, which are much lower intensity but still visible on this scale.…”

Hard X-ray Resonant Inelastic X-ray Scattering at the Advanced Photon Source

“…Meanwhile, Ellis et al have studied the doping dependence of the charge transfer excitations in detail [8]. Specifically, K-edge RIXS spectra were measured for La 2−x Sr x CuO 4 (LSCO) for 0 < x < 0.35 at three high-symmetry momentum-transfer (q) positions ( Figure 3).…”

“…The curves are vertically shifted with respect to each other for clarity. The insets show the combined, unshifted curves overlayed with each other.Figure taken from[8].…”