Electronic structure ofLa1−xSr

Abstract

The electronic structure of Lal Sr MnQ3 has been studied by photoemission and Q 1s x-rayabsorption spectroscopy. Spectra of the Mn 2p core levels and the valence bands for LaMnQ3 and SrMnQ3 have been analyzed using a configuration-interaction cluster model. The ground state of LaMnQ3 is found to be mixed d and d I states and that of SrMnQ3 to be heavily mixed d and d 1.states, rejecting their strong covalency. The character of the band gap of LaMnQ3 is of the p-to-d charge-transfer type while that of SrMnQ3 has considerable p-p character as well as p-d character. Holes doped into LaMnQ3 mainly of oxygen p character are coupled antiferromagnetically with the d local moments of the Mn + ions and become itinerant, thus aligning the Mn moments ferromagnetically. The changes in the electronic structure with carrier doping are not of the rigid band type: By La substitution for SrMnQ3, the so-called in-gap spectral weight (of e"~s ymmetry) appears with its peak located 1 -2 eV below the Fermi level and grows in intensity with increasing La concentration, while the spectral intensity of the eg~s tates above the Fermi level decreases, showing a transfer of spectral weight from the unoccupied to the occupied eg~s tates with electron doping. Meanwhile, the intensity at the Fermi level remains low even in the metallic phase (0.2~x~0.6). The energy shifts of core-level peaks and valence-band features with x suggest a downward shift of the Fermi level with hole doping, but the shift is found to be very small in the metallic phase. The importance of the orbital degeneracy of the e~~b and and possible orbital fiuctuations in the ferromagnetic phase are pointed out.

Charge Transfer in Iridate-Manganite Superlattices

“…The and Mn e g /t 2g ↓ orbitals) [18,37]. Within the molecular orbital picture, we expect the bonding (antibonding) states of Ir and Mn e g (3z 2 − r 2 ) orbitals to shift to lower (higher) energy.…”

The electronic structure and band hybridization of Co/Ti doped BaFe12O19

“…While ultraviolet photoemission suffers from the drawback that the technique is an extremely surface sensitive technique, resonant photoemission can be exploited to some effectiveness to ascertain charge localization [7] and [8] and provide some insight as to bonding confi guration [11], [12], [13], [14] and [15]. We have undertaken to use photoemission, with some theoretical support, to explore the local environment of the doping species (Co/Ti) within nanosized BaFe 12 O 19 particles.…”

“…Superlattices, notably of oxides, with unusual electronic and magnetic properties as well as charge transfer in complex oxides have been investigated by photoemission and resonant photoemission [7], [8], [9], [10], [11], [12], [13] and [14]. While ultraviolet photoemission suffers from the drawback that the technique is an extremely surface sensitive technique, resonant photoemission can be exploited to some effectiveness to ascertain charge localization [7] and [8] and provide some insight as to bonding confi guration [11], [12], [13], [14] and [15].…”

Orbital ordering inLa0.5Sr1.5MnO4studied by model Hartree-Fock calculation

“…The transfer integrals are given in terms of Slater-Koster parameters (ppσ), (ppπ), (pdσ) and (pdπ). In the present calculation, they are fixed at (ppσ) = 0.60 eV, (ppπ) = −0.15 eV, (pdσ) = −1.8 eV and (pdπ) = 0.81 eV for the averaged Mn-O distance of the Mn 3+ site [8,14,15]. Also, the atomic distance dependence of (pdσ) and (pdπ) or (ppσ) and (ppπ) are assumed to obey Harrison's rule d −3.5 or d −2 (ref.…”