Soft-x-ray-absorption studies of the location of extra charges induced by substitution in controlled-valence materials

Abbate, M.; Groot, Frank M. F. de; Fuggle, J. C.; Fujimori, A.; Tokura, Y.; Fujishima, Y.; Strebel, O.; Domke, M.; Kaindl, G.; Elp, J. van; Thole, B. T.; Sawatzky, G. A.; Sacchi, M.; Tsuda, Nobuo

doi:10.1103/physrevb.44.5419

Cited by 197 publications

(153 citation statements)

References 11 publications

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“…This value was consistent with x < 0.1 estimated from the Ti 2p XAS line-shape broadening [ Fig. 3(a)], which is a measure of the content of Ti 3+ component [22]. Since STO:Nb is a paramagnetic metal, we interpret that the valence of Ti is fluctuating between 3+ and 4+ with a time scale longer than that characteristic of a photoemission process (∼10 −16 s) [23], and PES provides a snapshot of this fluctuation to give a double-peaked Ti 2p spectrum.…”

supporting

confidence: 72%

Coherent and Incoherent Excitations of Electron-DopedSrTiO3

et al. 2008

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Resonant photoemission at the Ti 2p and O 1s edges on a Nb-doped SrTiO3 thin film revealed that the coherent state (CS) at the Fermi level (EF) had mainly Ti 3d character whereas the incoherent in-gap state (IGS) positioned ∼1.5 eV below EF had mixed character of Ti 3d and O 2p states. This indicates that the IGS is formed by a spectral-weight transfer from the CS and subsequent spectral-weight redistribution through d-p hybridization. We discuss the evolution of the excitation spectrum with 3d band filling and rationalize the IGS through a mechanism similar to that proposed by Haldane and Anderson. PACS numbers:SrTiO 3 (STO) is a perovskite-type oxide semiconductor with a band gap of 3.2 eV [1] and is considered to be one of the promising device materials in "oxide electronics." A variety of transition-metal oxides can be grown on STO with atomical flatness to show novel phenomena such as the high-mobility and magnetic interface of

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supporting

confidence: 72%

Coherent and Incoherent Excitations of Electron-DopedSrTiO3

et al. 2008

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“…On a virgin pad the Ti L-edge spectra of the homogeneous film as well as the growth defect reveal the typical absorption characteristic of a Ti 4+ configuration in STO in good agreement with literature 21,22 (see Fig. 2(b)).…”

confidence: 71%

“…Generally the observed shifts to lower photon energies indicate a lower valence and therefore the occurrence of Ti 3+ states. [25][26][27][28] The detailed line shape of our results can be compared to literature results of Abbate et al, 22 who presented Ti-XAS spectra for a systematic concentration series La 1-x Sr x TiO 3 with x = 0. . .…”

confidence: 67%

Evidence for multifilamentary valence changes in resistive switching SrTiO3 devices detected by transmission X-ray microscopy

Koehl¹,

Wasmund²,

Herpers³

et al. 2013

APL Materials

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Transmission X-ray microscopy is employed to detect nanoscale valence changes in resistive switching SrTiO3 thin film devices. By recording Ti L-edge spectra of samples in different resistive states, we could show that some spots with slightly distorted structure and a small reduction to Ti3+ are already present in the virgin films. In the ON-state, these spots are further reduced to Ti3+ to different degrees while the remaining film persists in the Ti4+ configuration. These observations are consistent with a self-accelerating reduction within pre-reduced extended growth defects

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“…No extra intensity was observed at ∼457 eV for any of these films, which would otherwise appear in the presence of Ti 3+ . 31,32 We thus confirm that virtually all Ti ions in the cobaltitetitanate films maintain the Ti 4+ oxidation state within an octahedral coordination environment, which in turn indicates that oxygen vacancies in the films are confined to the first coordination shell of Co. Given the persistent Ti 4+ O 6 octahedra and the corresponding localization of oxygen vacancies around Co, XAS was performed at the Co L 3,2 edge to probe simultaneously the oxygen coordination environment and oxidation state of the Co ions.…”

Section: -4supporting

confidence: 53%