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Iacocca E, Liu TM, Reid AH, Fu Z, Ruta S, Granitzka PW, Jal E, Bonetti S, Gray AX, Graves CE, Kukreja R, Chen Z, Higley DJ, Chase T, Le Guyader L, Hirsch K, Ohldag H, Schlotter WF, Dakovski GL, Coslovich G, Hoffmann MC, Carron S, Tsukamoto A, Kirilyuk A, Kimel AV, Rasing T, Stöhr J, Evans RFL, Ostler T, Chantrell RW, Hoefer MA, Silva TJ, Dürr HA. Spin-current-mediated rapid magnon localisation and coalescence after ultrafast optical pumping of ferrimagnetic alloys. Nat Commun 2019; 10:1756. [PMID: 30988403 PMCID: PMC6465265 DOI: 10.1038/s41467-019-09577-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 03/13/2019] [Indexed: 11/09/2022] Open
Abstract
Sub-picosecond magnetisation manipulation via femtosecond optical pumping has attracted wide attention ever since its original discovery in 1996. However, the spatial evolution of the magnetisation is not yet well understood, in part due to the difficulty in experimentally probing such rapid dynamics. Here, we find evidence of a universal rapid magnetic order recovery in ferrimagnets with perpendicular magnetic anisotropy via nonlinear magnon processes. We identify magnon localisation and coalescence processes, whereby localised magnetic textures nucleate and subsequently interact and grow in accordance with a power law formalism. A hydrodynamic representation of the numerical simulations indicates that the appearance of noncollinear magnetisation via optical pumping establishes exchange-mediated spin currents with an equivalent 100% spin polarised charge current density of 107 A cm-2. Such large spin currents precipitate rapid recovery of magnetic order after optical pumping. The magnon processes discussed here provide new insights for the stabilization of desired meta-stable states.
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Affiliation(s)
- E Iacocca
- Department of Applied Mathematics, University of Colorado, Boulder, CO, 80309, USA
- National Institute of Standards and Technology, Boulder, CO, 80305, USA
- Department of Physics, Division for Theoretical Physics, Chalmers University of Technology, Gothenburg, 412 96, Sweden
| | - T-M Liu
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - A H Reid
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - Z Fu
- School of Physics, Science, and Engineering, Tongji University, Shanghai, 200092, China
| | - S Ruta
- Department of Physics, University of York, York, YO10 5DD, UK
| | - P W Granitzka
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - E Jal
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - S Bonetti
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
- Department of Physics, Stockholm University, Stockholm, 106 91, Sweden
- Department of Molecular Science and Nanosystems, Ca' Foscari University of Venice, Venezia-Mestre, 30172, Italy
| | - A X Gray
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
- Department of Physics, Temple University, 1925 N. 12th St., Philadelphia, PA, 19122, USA
| | - C E Graves
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - R Kukreja
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - Z Chen
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - D J Higley
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - T Chase
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - L Le Guyader
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
- Spectroscopy & Coherent Scattering, European X-Ray Free-Electron Laser Facility GmbH, Holzkoppel 4, 22869, Schenefeld, Germany
| | - K Hirsch
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - H Ohldag
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - W F Schlotter
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - G L Dakovski
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - G Coslovich
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - M C Hoffmann
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - S Carron
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - A Tsukamoto
- Department of Electronics and Computer Science, Nihon University, 7-24-1 Narashino-dai Funabashi, Chiba, 274-8501, Japan
| | - A Kirilyuk
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - A V Kimel
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Th Rasing
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - J Stöhr
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - R F L Evans
- Department of Physics, University of York, York, YO10 5DD, UK
| | - T Ostler
- Physique des Matériaux et Nanostructures, Université de Liège, Liège, B-4000, Sart Tilman, Belgium
- Faculty of Arts, Computing, Engineering and Sciences, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK
| | - R W Chantrell
- Department of Physics, University of York, York, YO10 5DD, UK
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - M A Hoefer
- Department of Applied Mathematics, University of Colorado, Boulder, CO, 80309, USA
| | - T J Silva
- National Institute of Standards and Technology, Boulder, CO, 80305, USA
| | - H A Dürr
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA.
- Department of Physics and Astronomy, Uppsala University, Box 516, 751 20, Uppsala, Sweden.
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Gray AX, Jeong J, Aetukuri NP, Granitzka P, Chen Z, Kukreja R, Higley D, Chase T, Reid AH, Ohldag H, Marcus MA, Scholl A, Young AT, Doran A, Jenkins CA, Shafer P, Arenholz E, Samant MG, Parkin SSP, Dürr HA. Correlation-Driven Insulator-Metal Transition in Near-Ideal Vanadium Dioxide Films. Phys Rev Lett 2016; 116:116403. [PMID: 27035314 DOI: 10.1103/physrevlett.116.116403] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Indexed: 06/05/2023]
Abstract
We use polarization- and temperature-dependent x-ray absorption spectroscopy, in combination with photoelectron microscopy, x-ray diffraction, and electronic transport measurements, to study the driving force behind the insulator-metal transition in VO_{2}. We show that both the collapse of the insulating gap and the concomitant change in crystal symmetry in homogeneously strained single-crystalline VO_{2} films are preceded by the purely electronic softening of Coulomb correlations within V-V singlet dimers. This process starts 7 K (±0.3 K) below the transition temperature, as conventionally defined by electronic transport and x-ray diffraction measurements, and sets the energy scale for driving the near-room-temperature insulator-metal transition in this technologically promising material.
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Affiliation(s)
- A X Gray
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Physics, Temple University, 1925 North 12th Street, Philadelphia, Pennsylvania 19130, USA
| | - J Jeong
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - N P Aetukuri
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - P Granitzka
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Van der Waals-Zeeman Institute, University of Amsterdam, 1018XE Amsterdam, The Netherlands
| | - Z Chen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - R Kukreja
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - D Higley
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - T Chase
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - A H Reid
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - H Ohldag
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - M A Marcus
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - A Scholl
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - A T Young
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - A Doran
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - C A Jenkins
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - P Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - E Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA
| | - M G Samant
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - S S P Parkin
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - H A Dürr
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
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Fujii J, Salles BR, Sperl M, Ueda S, Kobata M, Kobayashi K, Yamashita Y, Torelli P, Utz M, Fadley CS, Gray AX, Braun J, Ebert H, Di Marco I, Eriksson O, Thunström P, Fecher GH, Stryhanyuk H, Ikenaga E, Minár J, Back CH, van der Laan G, Panaccione G. Identifying the electronic character and role of the Mn states in the valence band of (Ga,Mn)As. Phys Rev Lett 2013; 111:097201. [PMID: 24033065 DOI: 10.1103/physrevlett.111.097201] [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] [Received: 06/04/2013] [Indexed: 06/02/2023]
Abstract
We report high-resolution hard x-ray photoemission spectroscopy results on (Ga,Mn)As films as a function of Mn doping. Supported by theoretical calculations we identify, for both low (1%) and high (13%) Mn doping values, the electronic character of the states near the top of the valence band. Magnetization and temperature-dependent core-level photoemission spectra reveal how the delocalized character of the Mn states enables the bulk ferromagnetic properties of (Ga,Mn)As.
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Affiliation(s)
- J Fujii
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
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4
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Gray AX, Minár J, Ueda S, Stone PR, Yamashita Y, Fujii J, Braun J, Plucinski L, Schneider CM, Panaccione G, Ebert H, Dubon OD, Kobayashi K, Fadley CS. Bulk electronic structure of the dilute magnetic semiconductor Ga(1-x)Mn(x)As through hard X-ray angle-resolved photoemission. Nat Mater 2012; 11:957-962. [PMID: 23064495 DOI: 10.1038/nmat3450] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 09/10/2012] [Indexed: 06/01/2023]
Abstract
A detailed understanding of the origin of the magnetism in dilute magnetic semiconductors is crucial to their development for applications. Using hard X-ray angle-resolved photoemission (HARPES) at 3.2 keV, we investigate the bulk electronic structure of the prototypical dilute magnetic semiconductor Ga(0.97)Mn(0.03)As, and the reference undoped GaAs. The data are compared to theory based on the coherent potential approximation and fully relativistic one-step-model photoemission calculations including matrix-element effects. Distinct differences are found between angle-resolved, as well as angle-integrated, valence spectra of Ga(0.97)Mn(0.03)As and GaAs, and these are in good agreement with theory. Direct observation of Mn-induced states between the GaAs valence-band maximum and the Fermi level, centred about 400 meV below this level, as well as changes throughout the full valence-level energy range, indicates that ferromagnetism in Ga(1-x)Mn(x)As must be considered to arise from both p-d exchange and double exchange, thus providing a more unifying picture of this controversial material.
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Affiliation(s)
- A X Gray
- Department of Physics, University of California Davis, Davis, California 95616, USA.
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5
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Gray AX, Cooke DW, Krüger P, Bordel C, Kaiser AM, Moyerman S, Fullerton EE, Ueda S, Yamashita Y, Gloskovskii A, Schneider CM, Drube W, Kobayashi K, Hellman F, Fadley CS. Electronic structure changes across the metamagnetic transition in FeRh via hard X-ray photoemission. Phys Rev Lett 2012; 108:257208. [PMID: 23004654 DOI: 10.1103/physrevlett.108.257208] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Indexed: 06/01/2023]
Abstract
Stoichiometric FeRh undergoes a temperature-induced antiferromagnetic (AFM) to ferromagnetic (FM) transition at ~350 K. In this Letter, changes in the electronic structure accompanying this transition are investigated in epitaxial FeRh thin films via bulk-sensitive valence-band and core-level hard x-ray photoelectron spectroscopy with a photon energy of 5.95 keV. Clear differences between the AFM and FM states are observed across the entire valence-band spectrum and these are well reproduced using density-functional theory. Changes in the 2p core levels of Fe are also observed and interpreted using Anderson impurity model calculations. These results indicate that significant electronic structure changes over the entire valence-band region are involved in this AFM-FM transition.
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Affiliation(s)
- A X Gray
- Stanford Institute for Materials and Energy Science, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94029, USA
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6
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Schirmer M, Walz MM, Papp C, Kronast F, Gray AX, Balke B, Cramm S, Fadley CS, Steinrück HP, Marbach H. Fabrication of layered nanostructures by successive electron beam induced deposition with two precursors: protective capping of metallic iron structures. Nanotechnology 2011; 22:475304. [PMID: 22057093 DOI: 10.1088/0957-4484/22/47/475304] [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: 05/22/2023]
Abstract
We report on the stepwise generation of layered nanostructures via electron beam induced deposition (EBID) using organometallic precursor molecules in ultra-high vacuum (UHV). In a first step a metallic iron line structure was produced using iron pentacarbonyl; in a second step this nanostructure was then locally capped with a 2-3 nm thin titanium oxide-containing film fabricated from titanium tetraisopropoxide. The chemical composition of the deposited layers was analyzed by spatially resolved Auger electron spectroscopy. With spatially resolved x-ray absorption spectroscopy at the Fe L₃ edge, it was demonstrated that the thin capping layer prevents the iron structure from oxidation upon exposure to air.
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Affiliation(s)
- M Schirmer
- Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstraße 3, D-91058 Erlangen, Germany
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7
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Fujii J, Sperl M, Ueda S, Kobayashi K, Yamashita Y, Kobata M, Torelli P, Borgatti F, Utz M, Fadley CS, Gray AX, Monaco G, Back CH, van der Laan G, Panaccione G. Identification of different electron screening behavior between the bulk and surface of (Ga,Mn)As. Phys Rev Lett 2011; 107:187203. [PMID: 22107669 DOI: 10.1103/physrevlett.107.187203] [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] [Received: 07/25/2011] [Indexed: 05/31/2023]
Abstract
We report x-ray photoemission spectroscopy results on (Ga,Mn)As films as a function of both temperature and Mn doping. Analysis of Mn 2p core level spectra reveals the presence of a distinct electronic screening channel in the bulk, hitherto undetected in more surface sensitive analysis. Comparison with model calculations identifies the character of the Mn 3d electronic states and clarifies the role, and the difference between surface and bulk, of hybridization in mediating the ferromagnetic coupling in (Ga,Mn)As.
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Affiliation(s)
- J Fujii
- CNR Istituto Officina dei Materiali (IOM), Laboratorio TASC, S.S.14, Km 163.5, I-34149 Trieste, Italy
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Gray AX, Papp C, Ueda S, Balke B, Yamashita Y, Plucinski L, Minár J, Braun J, Ylvisaker ER, Schneider CM, Pickett WE, Ebert H, Kobayashi K, Fadley CS. Probing bulk electronic structure with hard X-ray angle-resolved photoemission. Nat Mater 2011; 10:759-764. [PMID: 21841798 DOI: 10.1038/nmat3089] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Accepted: 07/05/2011] [Indexed: 05/31/2023]
Abstract
Traditional ultraviolet/soft X-ray angle-resolved photoemission spectroscopy (ARPES) may in some cases be too strongly influenced by surface effects to be a useful probe of bulk electronic structure. Going to hard X-ray photon energies and thus larger electron inelastic mean-free paths should provide a more accurate picture of bulk electronic structure. We present experimental data for hard X-ray ARPES (HARPES) at energies of 3.2 and 6.0 keV. The systems discussed are W, as a model transition-metal system to illustrate basic principles, and GaAs, as a technologically-relevant material to illustrate the potential broad applicability of this new technique. We have investigated the effects of photon wave vector on wave vector conservation, and assessed methods for the removal of phonon-associated smearing of features and photoelectron diffraction effects. The experimental results are compared to free-electron final-state model calculations and to more precise one-step photoemission theory including matrix element effects.
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Affiliation(s)
- A X Gray
- Department of Physics, University of California Davis, Davis, California 95616, USA.
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Kaiser AM, Gray AX, Conti G, Son J, Greer A, Perona A, Rattanachata A, Saw AY, Bostwick A, Yang S, Yang SH, Gullikson EM, Kortright JB, Stemmer S, Fadley CS. Suppression of near-Fermi level electronic states at the interface in a LaNiO3/SrTiO3 superlattice. Phys Rev Lett 2011; 107:116402. [PMID: 22026689 DOI: 10.1103/physrevlett.107.116402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2011] [Indexed: 05/31/2023]
Abstract
Standing-wave-excited photoemission is used to study a SrTiO3/LaNiO3 superlattice. Rocking curves of core-level and valence band spectra are used to derive layer-resolved spectral functions, revealing a suppression of electronic states near the Fermi level in the multilayer as compared to bulk LaNiO3. Further analysis shows that the suppression of these states is not homogeneously distributed over the LaNiO3 layers but is more pronounced near the interfaces. Possible origins of this effect and its relationship to a previously observed metal-insulator-transition in ultrathin LaNiO3 films are discussed.
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Affiliation(s)
- A M Kaiser
- Department of Physics, University of California, Davis, California 95616, USA
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Boekelheide Z, Gray AX, Papp C, Balke B, Stewart DA, Ueda S, Kobayashi K, Hellman F, Fadley CS. Band gap and electronic structure of an epitaxial, semiconducting Cr0.80Al0.20 thin film. Phys Rev Lett 2010; 105:236404. [PMID: 21231489 DOI: 10.1103/physrevlett.105.236404] [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] [Received: 08/22/2010] [Indexed: 05/30/2023]
Abstract
Cr(1-x)Al(x) exhibits semiconducting behavior for x = 0.15-0.26. This Letter uses hard x-ray photoemission spectroscopy and density functional theory to further understand the semiconducting behavior. Photoemission measurements of an epitaxial Cr(0.80)Al(0.20) thin film show several features in the valence band region, including a gap at the Fermi energy (E(F)) for which the valence band edge is 95 ± 14 meV below E(F). Theory agrees well with the valence band measurements, and shows an incomplete gap at E(F) due to the hole band at M shifting almost below E(F).
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Affiliation(s)
- Z Boekelheide
- Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA.
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