Final-state effect on x-ray photoelectron spectrum of nominally<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>d</mml:mi><mml:mn>1</mml:mn></mml:msup></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>n</mml:mi></mml:math>-doped<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>d</mml:mi><mml:mn>0</mml:mn></mml:msup></mml:math>transition-metal oxides

Lin, Chungwei; Posadas, Agham; Hadamek, Tobias; Demkov, Alexander A.

doi:10.1103/physrevb.92.035110

Cited by 35 publications

(22 citation statements)

References 60 publications

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“…We like to point out here that the complex overoxidation mechanisms in LTO thin films have recently led to confusion about the line shape of the 2 p spectrum in d 1 transition metal oxides. It has been argued that photoemission final states always lead to a Ti 4+ signal even for stoichiometric LTO exclusively comprised of Ti 3+ ‐ions . Our measurements, however, give proof that this is not the case.…”

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confidence: 51%

“…In order to systematically investigate the effects of overoxidation, we fabricated a series of LTO thin films by pulsed laser deposition (PLD) at typical growth parameters on SrTiO 3 (STO) substrates in oxygen background pressures of 10 −5 mbar and lower. The structural characterization by X‐ray diffraction (XRD) and low‐energy electron diffraction (LEED) is depicted in Figure b,c and reveals a general trend: the quality of the diffraction pattern improves for films fabricated in lower oxygen pressure as judged by the Laue intensity oscillations in XRD and the overall contrast and width of the Bragg peaks in LEED.…”

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confidence: 99%

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Tailoring Materials for Mottronics: Excess Oxygen Doping of a Prototypical Mott Insulator

et al. 2018

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The Mott transistor is a paradigm for a new class of electronic devices-often referred to by the term Mottronics-which are based on charge correlations between the electrons. Since correlation-induced insulating phases of most oxide compounds are usually very robust, new methods have to be developed to push such materials right to the boundary to the metallic phase in order to enable the metal-insulator transition to be switched by electric gating. Here, it is demonstrated that thin films of the prototypical Mott insulator LaTiO grown by pulsed laser deposition under oxygen atmosphere are readily tuned by excess oxygen doping across the line of the band-filling controlled Mott transition in the electronic phase diagram. The detected insulator to metal transition is characterized by a strong change in resistivity of several orders of magnitude. The use of suitable substrates and capping layers to inhibit oxygen diffusion facilitates full control of the oxygen content and renders the films stable against exposure to ambient conditions. These achievements represent a significant advancement in control and tuning of the electronic properties of LaTiO thin films making it a promising channel material in future Mottronic devices.

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confidence: 51%

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confidence: 99%

Tailoring Materials for Mottronics: Excess Oxygen Doping of a Prototypical Mott Insulator

et al. 2018

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“…However, the shoulder positioned at a higher energy of 531.8 eV shows the existence of chemisorbed oxygen species on the sample. This has been proved in several previous studies [76][77][78][79]. Based on the calculation of free energy by the classical nucleation theory, most of the water-derived hydroxyl groups, such as OH radicals and H 2 O, have a high tendency to be chemisorbed near imperfections, such as defects (like vacancy levels) and grain boundaries.…”

Section: Research Articlementioning

confidence: 70%

Emerging photoluminescence from defective vanadium diselenide nanosheets

Ghobadi¹,

Ghobadi²,

Okyay³

et al. 2018

Photon. Res.

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In this paper, for the first time to our knowledge in the literature, we demonstrate photoluminescence from two-dimensional (2D) vanadium diselenide (VSe 2 ) nanosheets (NSs). The preparation of these nanostructures is carried out with a combinational method based on nanosecond pulsed laser ablation (PLA) and chemical exfoliation. For this aim, VSe 2 bulk is first ablated into nanoparticles (NPs) inside a water solution. Afterward, NPs are chemically exfoliated into NSs using lithium intercalation via ultrasonic treatment. Although VSe 2 is a semimetal in its bulk form, its nanostructures show photo-responsive behavior, and it turns into a strongly luminescent material when it is separated into NSs. Based on the obtained results, the surface defects induced during the PLA process are the origin of this photoluminescence from NSs. Our findings illustrate that this new material can be a promising semiconductor for photovoltaic and light emitting diode applications.

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“…An additional factor here could be the involvement of the highly delocalized electronic states responsible for the 2DEG in the screening, as has been seen, e.g. in transition-metal 2p spectra at higher energies [55], postulated recently for transition-metal 2p spectra in other oxides [56], and also discussed for La 3d spectra in several compounds [57]. It is also possible that these two states could be due to excitonlike effects [58].…”

Section: Sw Core-level Photoemission and Arpesmentioning

confidence: 99%

Energetic, spatial, and momentum character of the electronic structure at a buried interface: The two-dimensional electron gas between two metal oxides

Nemšák¹,

Conti²,

Gray³

et al. 2016

Phys. Rev. B

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The interfaces between two condensed phases often exhibit emergent physical properties that can lead to new physics and novel device applications and are the subject of intense study in many disciplines. We here apply experimental and theoretical techniques to the characterization of one such interesting interface system: the two-dimensional electron gas (2DEG) formed in multilayers consisting of SrTiO 3 (STO) and GdTiO 3 (GTO). This system has been the subject of multiple studies recently and shown to exhibit very high carrier charge densities and ferromagnetic effects, among other intriguing properties. We have studied a 2DEG-forming multilayer of the form [6 unit cells (u.c.) STO/3 u.c. of GTO] 20 using a unique array of photoemission techniques including soft and hard x-ray excitation, soft x-ray angle-resolved photoemission, core-level spectroscopy, resonant excitation, and standing-wave effects, as well as theoretical calculations of the electronic structure at several levels and of the actual photoemission process. Standing-wave measurements below and above a strong resonance have been exploited as a powerful method for studying the 2DEG depth distribution. We have thus characterized the spatial and momentum properties of this 2DEG in detail, determining via depth-distribution measurements that it is spread throughout the 6 u.c. layer of STO and measuring the momentum dispersion of its states. The experimental results are supported in several ways by theory, leading to a much more complete picture of the nature of this 2DEG and suggesting that oxygen vacancies are not the origin of it. Similar multitechnique photoemission studies of such states at buried interfaces, combined with comparable theory, will be a very fruitful future approach for exploring and modifying the fascinating world of buried-interface physics and chemistry.

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Final-state effect on x-ray photoelectron spectrum of nominallyd1andn-dopedd0transition-metal oxides

Abstract: We investigate the x-ray photoelectron spectroscopy (XPS)

Cited by 35 publications

References 60 publications

Tailoring Materials for Mottronics: Excess Oxygen Doping of a Prototypical Mott Insulator

Tailoring Materials for Mottronics: Excess Oxygen Doping of a Prototypical Mott Insulator

Emerging photoluminescence from defective vanadium diselenide nanosheets

Energetic, spatial, and momentum character of the electronic structure at a buried interface: The two-dimensional electron gas between two metal oxides

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