Optical conductivity and x-ray absorption spectra of the Mott-Hubbard compoundsRVO3(R=Sr, Ca, La, and Y)

Abstract

Core-level and valence-band optical spectra provide important information on highly correlated systems. The former corresponds to transitions from the core level to the conduction band, and it is usually related to the unoccupied electronic structure. The later corresponds to transitions from the valence band to the conduction band, and it is sometimes described in terms of the joint density of states. These spectra are usually treated separately due to the differences in the experimental and theoretical methods. We present here a combined description of the core-level and valence-level optical spectra of Mott-Hubbard compounds. In particular, we studied the O 1s x-ray absorption and the optical-conductivity spectra of SrVO 3 -CaVO 3 -LaVO 3 -YVO 3 . The experimental data were analyzed using an extended p-d cluster model solved by an exact diagonalization method. The results show that correlation effects alone cannot account for the experimental structures, and that crystal-field effects and exchange interactions are necessary to explain the spectra. We also show that there is a correspondence between the features in the charge-transfer region of both spectra.

Metal-insulator transition in low dimensional La0.75Sr0.25VO3 thin films

“…The prominent doublet feature in the energy range of 526 to 528 eV and 529 to 531 eV are assigned to the V3d t 2g and V 3d e g bands, respectively, and separated by ~ 2eV due to crystal field splitting. 15 The V 3d e g band overlaps with the La 5d and Sr 3d bands in the energy range from 529 to 536 eV. The qualitative features and positions of V 3d t 2g peaks remained unchanged with decreasing film thickness from 25 to 8 uc (metallic films) and were similar for grazing and normal incidences.…”

Ultrafast optical spectroscopy of the lowest energy excitations in the Mott insulator compound YVO3: Evidence for Hubbard-type excitons

“…The region of the optical spectra that is particularly sensitive to the orbital physics is the visible range, just above the gap of about 1.6 eV. The two peaks characterizing the reflectivity, with energies of 1.8 eV (HE) and 2.4 eV (SP) are largely debated 22,28,32,34,[41][42][43][44][45][46] and commonly assigned to d 28,41 However, the assignment to different multiplets of the peaks observed in the optical data has been controversial. 22,28,32,41 For E||c both excitations, at 1.8 and 2.4 eV, gain SW with decreasing temperature and approaching the spin-ordering transition at T SO = 116 K [ Fig.…”

Orbital superexchange and crystal field simultaneously at play in YVO3: Resonant inelastic x-ray scattering at the VLedge and the OKedge

“…In particular, the lowest peak at the O K edge at 530.1 eV is attributed to states of mixed O 2p-V 3d character. 49,52 A detailed analysis of the x-ray absorption spectra of YVO 3 can be found in Refs. 58 and 49.…”

“…The steep increase of the RIXS signal at 4.5 eV for E in = 530.1 eV at the O K edge is in good agreement with the onset of charge-transfer excitations observed in the optical conductivity. 30,51,52 However, the large intensity, exceeding the intensity of the elastic peak, points towards x-ray fluorescence emission, possibly superimposed by the charge-transfer excitations mentioned above.…”