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Local Real-Space View of the Achiral 1T-TiSe_{2} 2×2×2 Charge Density Wave. PHYSICAL REVIEW LETTERS 2018; 120:136404. [PMID: 29694190 DOI: 10.1103/physrevlett.120.136404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Indexed: 06/08/2023]
Abstract
The transition metal dichalcogenide 1T-TiSe_{2}-two-dimensional layered material undergoing a commensurate 2×2×2 charge density wave (CDW) transition with a weak periodic lattice distortion (PLD) below ≈200 K. Scanning tunneling microscopy (STM) combined with intentionally introduced interstitial Ti atoms allows us to go beyond the usual spatial resolution of STM and to intimately probe the three-dimensional character of the PLD. Furthermore, the inversion-symmetric achiral nature of the CDW in the z direction is revealed, contradicting the claimed existence of helical CDW stacking and associated chiral order. This study paves the way to a simultaneous real-space probing of both charge and structural reconstructions in CDW compounds.
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Selective Probing of Hidden Spin-Polarized States in Inversion-Symmetric Bulk MoS_{2}. PHYSICAL REVIEW LETTERS 2017; 118:086402. [PMID: 28282191 DOI: 10.1103/physrevlett.118.086402] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Indexed: 06/06/2023]
Abstract
Spin- and angle-resolved photoemission spectroscopy is used to reveal that a large spin polarization is observable in the bulk centrosymmetric transition metal dichalcogenide MoS_{2}. It is found that the measured spin polarization can be reversed by changing the handedness of incident circularly polarized light. Calculations based on a three-step model of photoemission show that the valley and layer-locked spin-polarized electronic states can be selectively addressed by circularly polarized light, therefore providing a novel route to probe these hidden spin-polarized states in inversion-symmetric systems as predicted by Zhang et al. [Nat. Phys. 10, 387 (2014).NPAHAX1745-247310.1038/nphys2933].
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Impact of electron-hole correlations on the 1T-TiSe_{2} electronic structure. PHYSICAL REVIEW LETTERS 2015; 114:086402. [PMID: 25768772 DOI: 10.1103/physrevlett.114.086402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Indexed: 06/04/2023]
Abstract
Several experiments have been performed on 1T-TiSe_{2} in order to identify whether the electronic structure is semimetallic or semiconducting without reaching a consensus. In this Letter, we theoretically study the impact of electron-hole and electron-phonon correlations on the bare semimetallic and semiconducting electronic structure. The resulting electron spectral functions provide a direct comparison of both cases and demonstrate that 1T-TiSe_{2} is of predominant semiconducting character with some spectral weight crossing the Fermi level.
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Doping nature of native defects in 1T-TiSe2. PHYSICAL REVIEW LETTERS 2014; 112:197001. [PMID: 24877961 DOI: 10.1103/physrevlett.112.197001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Indexed: 06/03/2023]
Abstract
The transition-metal dichalcogenide 1T-TiSe2 is a quasi-two-dimensional layered material with a charge density wave (CDW) transition temperature of T(CDW) ≈ 200 K. Self-doping effects for crystals grown at different temperatures introduce structural defects, modify the temperature-dependent resistivity, and strongly perturbate the CDW phase. Here, we study the structural and doping nature of such native defects combining scanning tunneling microscopy or spectroscopy and ab initio calculations. The dominant native single atom dopants we identify in our single crystals are intercalated Ti atoms, Se vacancies, and Se substitutions by residual iodine and oxygen.
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Mapping of electron-hole excitations in the charge-density-wave system 1T-TiSe2 using resonant inelastic x-ray scattering. PHYSICAL REVIEW LETTERS 2012; 109:047401. [PMID: 23006106 DOI: 10.1103/physrevlett.109.047401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Indexed: 06/01/2023]
Abstract
In high-resolution resonant inelastic x-ray scattering at the Ti L edge of the charge-density-wave system 1T-TiSe(2), we observe sharp low energy loss peaks from electron-hole pair excitations developing at low temperature. These excitations are strongly dispersing as a function of the transferred momentum of light. We show that the unoccupied bands close to the Fermi level can effectively be probed in this broadband material. Furthermore, we extract the order parameter of the charge-density-wave phase from temperature-dependent measurements.
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Exciton condensation driving the periodic lattice distortion of 1T-TiSe2. PHYSICAL REVIEW LETTERS 2011; 106:106404. [PMID: 21469817 DOI: 10.1103/physrevlett.106.106404] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Indexed: 05/30/2023]
Abstract
We address the lattice deformation of 1T-TiSe2 within the exciton condensate phase. We show that, at low temperature, condensed excitons influence the lattice through electron-phonon interaction. It is found that at zero temperature, in the exciton condensate phase of 1T-TiSe2, this exciton condensate exerts a force on the lattice generating ionic displacements comparable in amplitude to what is measured in experiment. This is thus the first quantitative estimation of the amplitude of the periodic lattice distortion observed in 1T-TiSe2 as a consequence of the exciton condensate phase.
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Evidence for an excitonic insulator phase in 1T-TiSe2. PHYSICAL REVIEW LETTERS 2007; 99:146403. [PMID: 17930692 DOI: 10.1103/physrevlett.99.146403] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Indexed: 05/25/2023]
Abstract
We present a new high-resolution angle-resolved photoemission study of 1T-TiSe2 in both its room-temperature, normal phase and its low-temperature, charge-density wave phase. At low temperature the photoemission spectra are strongly modified, with large band renormalizations at high-symmetry points of the Brillouin zone and a very large transfer of spectral weight to backfolded bands. A calculation of the theoretical spectral function for an excitonic insulator phase reproduces the experimental features with very good agreement. This gives strong evidence in favor of the excitonic insulator scenario as a driving force for the charge-density wave transition in 1T-TiSe2.
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Photoemission of a quantum cavity with a nonmagnetic spin separator. PHYSICAL REVIEW LETTERS 2005; 95:126401. [PMID: 16197090 DOI: 10.1103/physrevlett.95.126401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2004] [Indexed: 05/04/2023]
Abstract
Quantum well states are a consequence of confinement in a quantum cavity. In this study we investigate with photoemission the influence of the interface electronic structure on the quantum well state energy dispersion in ultrathin Mg(0001) films on W(110). Coupling between the sp-derived quantum well states and the substrate across the interface becomes manifest in a deviation from free electronlike dispersion behavior. Most importantly, we observe a marked level splitting, which is interpreted as due to the Rashba effect at the interface. Such an interfacial electron beam splitting on materials with strong spin-orbit coupling is an essential ingredient for novel spintronic devices. The combination of a quantum cavity with a heavy, electron reflecting substrate reveals spin-splitting effects in ultrathin films without conventional magnetism being involved.
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Excited states mapped by secondary photoemission. PHYSICAL REVIEW LETTERS 2004; 93:107601. [PMID: 15447452 DOI: 10.1103/physrevlett.93.107601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2004] [Indexed: 05/24/2023]
Abstract
We report on angle-resolved photoemission (ARPES) experiments on Cu(110) using Mg K(alpha) radiation. The secondary emission (SE) fine structure of electrons below 50 eV is found to map the empty band structure relevant for absolute band mapping in ARPES. The finding is based on a direct comparison of our experiments with very low-energy electron diffraction data [Phys. Rev. Lett. 81, 4943 (1998)]] recently shown to map the unoccupied states representing the photoemission final-state. This suggests a new theoretical approach to the SE process treating the outgoing electron state as the time-reversed diffraction state.
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Electronic structure of the YH3 phase from angle-resolved photoemission spectroscopy. PHYSICAL REVIEW LETTERS 2003; 90:196804. [PMID: 12785971 DOI: 10.1103/physrevlett.90.196804] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2002] [Indexed: 05/24/2023]
Abstract
Yttrium can be loaded with hydrogen up to high concentrations causing dramatic structural and electronic changes of the host lattice. We report on angle-resolved photoemission experiments of the Y trihydride phase. Most importantly, we find the absence of metal d bands at the Fermi level and a set of flat, H-induced bands located at much higher binding energy than predicted, indicating an increased electron affinity at H sites.
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Formation of a stable decagonal quasicrystalline Al-Pd-Mn surface layer. PHYSICAL REVIEW LETTERS 2001; 87:195506. [PMID: 11690424 DOI: 10.1103/physrevlett.87.195506] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2001] [Indexed: 05/23/2023]
Abstract
We report the in situ formation of an ordered equilibrium decagonal Al-Pd-Mn quasicrystal overlayer on the fivefold symmetric surface of an icosahedral Al-Pd-Mn monograin. The decagonal structure of the epilayer is evidenced by x-ray photoelectron diffraction, low-energy electron diffraction, and electron backscatter diffraction. This overlayer is also characterized by a reduced density of states near the Fermi edge as expected for quasicrystals. This is the first time that a millimeter-size surface of the stable decagonal Al-Pd-Mn is obtained, studied, and compared to its icosahedral counterpart.
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Electronic structure of high- and low- temperature c(2 x 2)-Na/Al(001) phases from angle-scanned ultraviolet photoemission. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:5893-5900. [PMID: 9986555 DOI: 10.1103/physrevb.54.5893] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Orientation of adsorbed C60 molecules determined via x-ray photoelectron diffraction. PHYSICAL REVIEW LETTERS 1996; 76:4733-4736. [PMID: 10061367 DOI: 10.1103/physrevlett.76.4733] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Final-state scattering in angle-resolved ultraviolet photoemission from copper. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:10209-10216. [PMID: 9982589 DOI: 10.1103/physrevb.53.10209] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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16
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k-space mapping of majority and minority bands on the Fermi surface of Nickel below and above the Curie temperature. PHYSICAL REVIEW LETTERS 1996; 76:1150-1153. [PMID: 10061646 DOI: 10.1103/physrevlett.76.1150] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Direct structure determination of a composite double-layer surface alloy by x-ray photoelectron diffraction: p(2 x 2)-Na/Al(111). PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:R2313-R2316. [PMID: 9981399 DOI: 10.1103/physrevb.52.r2313] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Local structure of c(2 x 2)-Na on Al(001): Experimental evidence for the coexistence of intermixing and on-surface adsorption. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:14516-14524. [PMID: 9975674 DOI: 10.1103/physrevb.50.14516] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Complete Fermi surface mapping of Bi2Sr2CaCu2O8+x(001): Coexistence of short range antiferromagnetic correlations and metallicity in the same phase. PHYSICAL REVIEW LETTERS 1994; 72:2757-2760. [PMID: 10055969 DOI: 10.1103/physrevlett.72.2757] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Local epitaxy of Ag on Bi2Sr2CaCu2O8+x(001). PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:6732-6735. [PMID: 10009245 DOI: 10.1103/physrevb.48.6732] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Simultaneous analysis of multiple extended x-ray-absorption fine-structure spectra: Application to studies of buried Ge-Si interfaces. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 45:13579-13590. [PMID: 10001447 DOI: 10.1103/physrevb.45.13579] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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M and N core excitations in zirconium. PHYSICAL REVIEW. B, CONDENSED MATTER 1990; 42:5984-5989. [PMID: 9994673 DOI: 10.1103/physrevb.42.5984] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Nondipole channels in the electron-energy-loss structure near the 3s edge of copper. PHYSICAL REVIEW. B, CONDENSED MATTER 1990; 42:5369-5372. [PMID: 9996113 DOI: 10.1103/physrevb.42.5369] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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L and M edges of copper: Theory and experiment. PHYSICAL REVIEW. B, CONDENSED MATTER 1990; 41:11760-11769. [PMID: 9993622 DOI: 10.1103/physrevb.41.11760] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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L2,3 edge of silicon: Theory and experiment. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 38:5392-5396. [PMID: 9946977 DOI: 10.1103/physrevb.38.5392] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Electronic excitations in the transition metals V, Zr, Nb, Mo, and Ta. PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 35:3062-3068. [PMID: 9941801 DOI: 10.1103/physrevb.35.3062] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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