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Hartley P, Egdell RG, Zhang KHL, Hohmann MV, Piper LFJ, Morgan DJ, Scanlon DO, Williamson BAD, Regoutz A. Experimental and Theoretical Study of the Electronic Structures of Lanthanide Indium Perovskites LnInO 3. J Phys Chem C Nanomater Interfaces 2021; 125:6387-6400. [PMID: 33868543 PMCID: PMC8042864 DOI: 10.1021/acs.jpcc.0c11592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/19/2021] [Indexed: 06/12/2023]
Abstract
Ternary lanthanide indium oxides LnInO3 (Ln = La, Pr, Nd, Sm) were synthesized by high-temperature solid-state reaction and characterized by X-ray powder diffraction. Rietveld refinement of the powder patterns showed the LnInO3 materials to be orthorhombic perovskites belonging to the space group Pnma, based on almost-regular InO6 octahedra and highly distorted LnO12 polyhedra. Experimental structural data were compared with results from density functional theory (DFT) calculations employing a hybrid Hamiltonian. Valence region X-ray photoelectron and K-shell X-ray emission and absorption spectra of the LnInO3 compounds were simulated with the aid of the DFT calculations. Photoionization of lanthanide 4f orbitals gives rise to a complex final-state multiplet structure in the valence region for the 4f n compounds PrInO3, NdInO3, and SmInO3, and the overall photoemission spectral profiles were shown to be a superposition of final-state 4f n-1 terms onto the cross-section weighted partial densities of states from the other orbitals. The occupied 4f states are stabilized in moving across the series Pr-Nd-Sm. Band gaps were measured using diffuse reflectance spectroscopy. These results demonstrated that the band gap of LaInO3 is 4.32 eV, in agreement with DFT calculations. This is significantly larger than a band gap of 2.2 eV first proposed in 1967 and based on the idea that In 4d states lie above the top of the O 2p valence band. However, both DFT and X-ray spectroscopy show that In 4d is a shallow core level located well below the bottom of the valence band. Band gaps greater than 4 eV were observed for NdInO3 and SmInO3, but a lower gap of 3.6 eV for PrInO3 was shown to arise from the occupied Pr 4f states lying above the main O 2p valence band.
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Affiliation(s)
- P. Hartley
- Department
of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K.
| | - R. G. Egdell
- Department
of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K.
| | - K. H. L. Zhang
- Department
of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K.
- State
Key Laboratory of Physical Chemistry of Solid Surfaces, College of
Chemistry and Chemical Engineering, Xiamen
University, Xiamen 361005, People’s Republic
of China
| | - M. V. Hohmann
- Department
of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K.
- Institute
of Materials Science, Surface Science Division, Technische Universität Darmstadt, Darmstadt 64287, Germany
| | - L. F. J. Piper
- WMG, The University of Warwick, Coventry CV4 7AL, U.K.
- Department
of Applied Physics & Astronomy, Binghamton
University, State University of New York, Binghamton, New York 13902, United States
| | - D. J. Morgan
- Cardiff Catalysis
Institute, School of Chemistry, Cardiff
University, Park Place, Cardiff CF10
3AT, U.K.
| | - D. O. Scanlon
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
- Thomas
Young Centre, University College London, Gower Street, London WC1E 6BT, U.K.
- Diamond
Light Source Ltd., Diamond
House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11
0DE, U.K.
| | - B. A. D. Williamson
- Department
of Materials Science and Engineering, Norwegian
University of Science and Technology (NTNU), Trondheim 7491, Norway
| | - A. Regoutz
- Department
of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K.
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
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Lebens-Higgins Z, Scanlon DO, Paik H, Sallis S, Nie Y, Uchida M, Quackenbush NF, Wahila MJ, Sterbinsky GE, Arena DA, Woicik JC, Schlom DG, Piper LFJ. Direct Observation of Electrostatically Driven Band Gap Renormalization in a Degenerate Perovskite Transparent Conducting Oxide. Phys Rev Lett 2016; 116:027602. [PMID: 26824566 DOI: 10.1103/physrevlett.116.027602] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Indexed: 05/28/2023]
Abstract
We have directly measured the band gap renormalization associated with the Moss-Burstein shift in the perovskite transparent conducting oxide (TCO), La-doped BaSnO_{3}, using hard x-ray photoelectron spectroscopy. We determine that the band gap renormalization is almost entirely associated with the evolution of the conduction band. Our experimental results are supported by hybrid density functional theory supercell calculations. We determine that unlike conventional TCOs where interactions with the dopant orbitals are important, the band gap renormalization in La-BaSnO_{3} is driven purely by electrostatic interactions.
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Affiliation(s)
- Z Lebens-Higgins
- Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, 10 New York 13902, USA
| | - D O Scanlon
- Kathleen Lonsdale Materials Chemistry, Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - H Paik
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA
| | - S Sallis
- Materials science and Engineering, Applied Physics and Astronomy, Binghamton University, Binghamton, 10 New York 13902, USA
| | - Y Nie
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York 14853, USA‡
| | - M Uchida
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York 14853, USA‡
- Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan
| | - N F Quackenbush
- Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, 10 New York 13902, USA
| | - M J Wahila
- Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, 10 New York 13902, USA
| | - G E Sterbinsky
- National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973, USA§
| | - Dario A Arena
- National Synchrotron Light Source-II, Basic Energy Sciences Directorate, Brookhaven National Laboratory, Upton, New York 11973, USA¶
| | - J C Woicik
- Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - D G Schlom
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, United States
| | - L F J Piper
- Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, 10 New York 13902, USA
- Materials science and Engineering, Applied Physics and Astronomy, Binghamton University, Binghamton, 10 New York 13902, USA
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Zhang KHL, Du Y, Sushko PV, Bowden ME, Shutthanandan V, Qiao L, Cao GX, Gai Z, Sallis S, Piper LFJ, Chambers SA. Electronic and magnetic properties of epitaxial perovskite SrCrO₃(0 0 1). J Phys Condens Matter 2015; 27:245605. [PMID: 26037231 DOI: 10.1088/0953-8984/27/24/245605] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We have investigated the intrinsic properties of SrCrO3 epitaxial thin films synthesized by molecular beam epitaxy. We find compelling evidence that SrCrO3 is a correlated metal. X-ray photoemission valence band and O K-edge x-ray absorption spectra indicate a strongly hybridized Cr3d-O2p state crossing the Fermi level, leading to metallic behavior. Comparison between valence band spectra near the Fermi level and the densities of states calculated using density functional theory (DFT) suggests the presence of coherent and incoherent states and points to strong electron correlation effects. The magnetic susceptibility can be described by Pauli paramagnetism at temperatures above 100 K, but reveals antiferromagnetic behavior at lower temperatures, possibly resulting from orbital ordering.
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Affiliation(s)
- K H L Zhang
- Physical Sciences Division, Fundamental & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA. Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, UK
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Laverock J, Chen B, Preston ARH, Newby D, Piper LFJ, Tung LD, Balakrishnan G, Glans PA, Guo JH, Smith KE. Low-energy V t2g orbital excitations in NdVO3. J Phys Condens Matter 2014; 26:455603. [PMID: 25336521 DOI: 10.1088/0953-8984/26/45/455603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The electronic structure of NdVO(3) and YVO(3) has been investigated as a function of sample temperature using resonant inelastic soft x-ray scattering at the V L(3)-edge. Most of the observed spectral features are in good agreement with an atomic crystal-field multiplet model. However, a low energy feature is observed at ∼ 0.4 eV that cannot be explained by crystal-field arguments. The resonant behaviour of this feature establishes it as due to excitations of the V t(2g) states. Moreover, this feature exhibits a strong sample temperature dependence, reaching maximum intensity in the orbitally-ordered phase of NdVO(3), before becoming suppressed at low temperatures. This behaviour indicates that the origin of this feature is a collective orbital excitation, i.e. the bi-orbiton.
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Affiliation(s)
- J Laverock
- Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA
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Cho SW, Newby D, DeMasi A, Smith KE, Piper LFJ, Jones TS. Determination of the individual atomic site contribution to the electronic structure of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA). J Chem Phys 2013; 139:184711. [PMID: 24320295 DOI: 10.1063/1.4829764] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have studied the element and orbital-specific electronic structure of thin films of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) using a combination of synchrotron radiation-exited resonant x-ray emission spectroscopy, x-ray absorption spectroscopy, x-ray photoelectron spectroscopy, as well as density functional theory calculations. Resonant and non-resonant x-ray emission spectroscopies were used to measure the C and O 2p partial densities of state in PTCDA. Furthermore, resonant x-ray emission at the C and O K-edges is shown to be able to measure the partial densities of states associated with individual atomic sites. The flat molecular orientation of PTCDA on various substrates is explained in terms of the carbonyl O atom acting as a hydrogen-bond acceptor leading to multiple in-plane intermolecular C=O···H-C hydrogen bonding between carbonyl groups and the perylene core of the neighboring PTCDA molecules. We support this conclusion by comparison of our calculations to measurements of the electronic structure using element-, site-, and orbital-selective C and O K-edge resonant x-ray emission spectroscopy, and photoemission spectroscopy.
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Affiliation(s)
- S W Cho
- Department of Physics, Yonsei University, Wonju, Gangwon-do 220-710, Korea
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Quackenbush NF, Tashman JW, Mundy JA, Sallis S, Paik H, Misra R, Moyer JA, Guo JH, Fischer DA, Woicik JC, Muller DA, Schlom DG, Piper LFJ. Nature of the metal insulator transition in ultrathin epitaxial vanadium dioxide. Nano Lett 2013; 13:4857-4861. [PMID: 24000961 DOI: 10.1021/nl402716d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We have combined hard X-ray photoelectron spectroscopy with angular dependent O K-edge and V L-edge X-ray absorption spectroscopy to study the electronic structure of metallic and insulating end point phases in 4.1 nm thick (14 units cells along the c-axis of VO2) films on TiO2(001) substrates, each displaying an abrupt MIT centered at ~300 K with width <20 K and a resistance change of ΔR/R > 10(3). The dimensions, quality of the films, and stoichiometry were confirmed by a combination of scanning transmission electron microscopy with electron energy loss spectroscopy, X-ray spectroscopy, and resistivity measurements. The measured end point phases agree with their bulk counterparts. This clearly shows that, apart from the strain induced change in transition temperature, the underlying mechanism of the MIT for technologically relevant dimensions must be the same as the bulk for this orientation.
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Affiliation(s)
- N F Quackenbush
- Department of Physics, Applied Physics and Astronomy, Binghamton University , Binghamton, New York 13902, United States
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Chen B, Laverock J, Piper LFJ, Preston ARH, Cho SW, DeMasi A, Smith KE, Scanlon DO, Watson GW, Egdell RG, Glans PA, Guo JH. The band structure of WO3 and non-rigid-band behaviour in Na0.67WO3 derived from soft x-ray spectroscopy and density functional theory. J Phys Condens Matter 2013; 25:165501. [PMID: 23553445 DOI: 10.1088/0953-8984/25/16/165501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The electronic structure of single-crystal WO3 and Na0.67WO3 (a sodium-tungsten bronze) has been measured using soft x-ray absorption and resonant soft x-ray emission oxygen K-edge spectroscopies. The spectral features show clear differences in energy and intensity between WO3 and Na0.67WO3. The x-ray emission spectrum of metallic Na0.67WO3 terminates in a distinct Fermi edge. The rigid-band model fails to explain the electronic structure of Na0.67WO3 in terms of a simple addition of electrons to the conduction band of WO3. Instead, Na bonding and Na 3s-O 2p hybridization need to be considered for the sodium-tungsten bronze, along with occupation of the bottom of the conduction band. Furthermore, the anisotropy in the band structure of monoclinic γ-WO3 revealed by the experimental spectra with orbital-resolved geometry is explained via density functional theory calculations. For γ-WO3 itself, good agreement is found between the experimental O K-edge spectra and the theoretical partial density of states of O 2p orbitals. Indirect and direct bandgaps of insulating WO3 are determined from extrapolating separations between spectral leading edges and accounting for the core-hole energy shift in the absorption process. The O 2p non-bonding states show upward band dispersion as a function of incident photon energy for both compounds, which is explained using the calculated band structure and experimental geometry.
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Affiliation(s)
- B Chen
- Department of Physics, Boston University, Boston, MA 02215, USA.
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DeMasi A, Cho SW, Piper LFJ, Preston ARH, Smith KE, Allenbaugh RJ, Barksdale WA, Doerrer LH. Electronic structure of N,N′-ethylene-bis(1,1,1-trifluoropentane-2,4-dioneiminato)-copper(ii) (Cu-TFAC), from soft X-ray spectroscopies and density functional theory calculations. Phys Chem Chem Phys 2010; 12:3171-7. [DOI: 10.1039/b926277f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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DeMasi A, Piper LFJ, Zhang Y, Reid I, Wang S, Smith KE, Downes JE, Peltekis N, McGuinness C, Matsuura A. Electronic structure of the organic semiconductor Alq3 (aluminum tris-8-hydroxyquinoline) from soft x-ray spectroscopies and density functional theory calculations. J Chem Phys 2009; 129:224705. [PMID: 19071937 DOI: 10.1063/1.3030975] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The element-specific electronic structure of the organic semiconductor aluminum tris-8-hydroxyquinoline (Alq(3)) has been studied using a combination of resonant x-ray emission spectroscopy, x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory (DFT) calculations. Resonant and nonresonant x-ray emission spectroscopy were used to measure directly the carbon, nitrogen and oxygen 2p partial densities of states in Alq(3), and good agreement was found with the results of DFT calculations. Furthermore, resonant x-ray emission at the carbon K-edge is shown to be able to measure the partial density of states associated with individual C sites. Finally, comparison of previous x-ray emission studies and the present data reveal the presence of clear photon-induced damage in the former.
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Affiliation(s)
- A DeMasi
- Department of Physics, Boston University, Boston, Massachussets 02215, USA
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10
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Walsh A, Da Silva JLF, Wei SH, Körber C, Klein A, Piper LFJ, DeMasi A, Smith KE, Panaccione G, Torelli P, Payne DJ, Bourlange A, Egdell RG. Nature of the band gap of In2O3 revealed by first-principles calculations and x-ray spectroscopy. Phys Rev Lett 2008; 100:167402. [PMID: 18518246 DOI: 10.1103/physrevlett.100.167402] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Indexed: 05/26/2023]
Abstract
Bulk and surface sensitive x-ray spectroscopic techniques are applied in tandem to show that the valence band edge for In2O3 is found significantly closer to the bottom of the conduction band than expected on the basis of the widely quoted bulk band gap of 3.75 eV. First-principles theory shows that the upper valence bands of In2O3 exhibit a small dispersion and the conduction band minimum is positioned at Gamma. However, direct optical transitions give a minimal dipole intensity until 0.8 eV below the valence band maximum. The results set an upper limit on the fundamental band gap of 2.9 eV.
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Affiliation(s)
- Aron Walsh
- National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
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Zhang Y, Wang S, Demasi A, Reid I, Piper LFJ, Matsuura AY, Downes JE, Smith. KE. Soft X-ray spectroscopy study of electronic structure in the organic semiconductor titanyl phthalocyanine (TiO-Pc). ACTA ACUST UNITED AC 2008. [DOI: 10.1039/b717224a] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Colakerol L, Veal TD, Jeong HK, Plucinski L, DeMasi A, Learmonth T, Glans PA, Wang S, Zhang Y, Piper LFJ, Jefferson PH, Fedorov A, Chen TC, Moustakas TD, McConville CF, Smith KE. Quantized electron accumulation states in indium nitride studied by angle-resolved photoemission spectroscopy. Phys Rev Lett 2006; 97:237601. [PMID: 17280245 DOI: 10.1103/physrevlett.97.237601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Indexed: 05/13/2023]
Abstract
Electron accumulation states in InN have been measured using high resolution angle-resolved photoemission spectroscopy (ARPES). The electrons in the accumulation layer have been discovered to reside in quantum well states. ARPES was also used to measure the Fermi surface of these quantum well states, as well as their constant binding energy contours below the Fermi level E(F). The energy of the Fermi level and the size of the Fermi surface for these quantum well states could be controlled by varying the method of surface preparation. This is the first unambiguous observation that electrons in the InN accumulation layer are quantized and the first time the Fermi surface associated with such states has been measured.
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Affiliation(s)
- Leyla Colakerol
- Department of Physics, Boston University, Boston, Massachusetts 02215, USA
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