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Zhou X, He S, Liu G, Zhao L, Yu L, Zhang W. New developments in laser-based photoemission spectroscopy and its scientific applications: a key issues review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:062101. [PMID: 29460857 DOI: 10.1088/1361-6633/aab0cc] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The significant progress in angle-resolved photoemission spectroscopy (ARPES) in last three decades has elevated it from a traditional band mapping tool to a precise probe of many-body interactions and dynamics of quasiparticles in complex quantum systems. The recent developments of deep ultraviolet (DUV, including ultraviolet and vacuum ultraviolet) laser-based ARPES have further pushed this technique to a new level. In this paper, we review some latest developments in DUV laser-based photoemission systems, including the super-high energy and momentum resolution ARPES, the spin-resolved ARPES, the time-of-flight ARPES, and the time-resolved ARPES. We also highlight some scientific applications in the study of electronic structure in unconventional superconductors and topological materials using these state-of-the-art DUV laser-based ARPES. Finally we provide our perspectives on the future directions in the development of laser-based photoemission systems.
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Affiliation(s)
- Xingjiang Zhou
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China. Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China
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Yamada K, Souma S, Yamauchi K, Shimamura N, Sugawara K, Trang CX, Oguchi T, Ueno K, Takahashi T, Sato T. Ultrathin Bismuth Film on 1T-TaS 2: Structural Transition and Charge-Density-Wave Proximity Effect. NANO LETTERS 2018; 18:3235-3240. [PMID: 29701062 DOI: 10.1021/acs.nanolett.8b01003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We have fabricated bismuth (Bi) ultrathin films on a charge-density-wave (CDW) compound 1T-TaS2 and elucidated electronic states by angle-resolved photoemission spectroscopy and first-principles band-structure calculations. We found that the Bi film on 1T-TaS2 undergoes a structural transition from (111) to (110) upon reducing the film thickness, accompanied by a drastic change in the energy band structure. We also revealed that while two-bilayer-thick Bi(110) film on Si(111) is characterized by a dispersive band touching the Fermi level ( EF), the energy band of the same film on 1T-TaS2 exhibits holelike dispersion with a finite energy gap at EF. We discuss the origin of such intriguing differences in terms of the CDW proximity effect.
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Affiliation(s)
- Keiko Yamada
- Department of Physics , Tohoku University , Sendai 980-8578 , Japan
| | - Seigo Souma
- Center for Spintronics Research Network , Tohoku University , Sendai 980-8577 , Japan
- WPI Research Center, Advanced Institute for Materials Research , Tohoku University , Sendai 980-8577 , Japan
| | - Kunihiko Yamauchi
- Institute of Scientific and Industrial Research , Osaka University , Ibaraki, Osaka 567-0047 , Japan
| | | | - Katsuaki Sugawara
- Center for Spintronics Research Network , Tohoku University , Sendai 980-8577 , Japan
- WPI Research Center, Advanced Institute for Materials Research , Tohoku University , Sendai 980-8577 , Japan
| | - Chi Xuan Trang
- Department of Physics , Tohoku University , Sendai 980-8578 , Japan
| | - Tamio Oguchi
- Institute of Scientific and Industrial Research , Osaka University , Ibaraki, Osaka 567-0047 , Japan
| | - Keiji Ueno
- Department of Chemistry, Graduate School of Science and Engineering , Saitama University , Saitama 338-8570 , Japan
| | - Takashi Takahashi
- Department of Physics , Tohoku University , Sendai 980-8578 , Japan
- Center for Spintronics Research Network , Tohoku University , Sendai 980-8577 , Japan
- WPI Research Center, Advanced Institute for Materials Research , Tohoku University , Sendai 980-8577 , Japan
| | - Takafumi Sato
- Department of Physics , Tohoku University , Sendai 980-8578 , Japan
- Center for Spintronics Research Network , Tohoku University , Sendai 980-8577 , Japan
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Fujimori SI. Band structures of 4f and 5f materials studied by angle-resolved photoelectron spectroscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:153002. [PMID: 26974712 DOI: 10.1088/0953-8984/28/15/153002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Recent remarkable progress in angle-resolved photoelectron spectroscopy (ARPES) has enabled the direct observation of the band structures of 4f and 5f materials. In particular, ARPES with various light sources such as lasers (hν ~ 7 eV) or high-energy synchrotron radiations (hν >/~ 400 eV) has shed light on the bulk band structures of strongly correlated materials with energy scales of a few millielectronvolts to several electronvolts. The purpose of this paper is to summarize the behaviors of 4f and 5f band structures of various rare-earth and actinide materials observed by modern ARPES techniques, and understand how they can be described using various theoretical frameworks. For 4f-electron materials, ARPES studies of CeMIn5(M = Rh, Ir, and Co) and YbRh2Si2 with various incident photon energies are summarized. We demonstrate that their 4f electronic structures are essentially described within the framework of the periodic Anderson model, and that the band-structure calculation based on the local density approximation cannot explain their low-energy electronic structures. Meanwhile, electronic structures of 5f materials exhibit wide varieties ranging from itinerant to localized states. For itinerant U5f compounds such as UFeGa5, their electronic structures can be well-described by the band-structure calculation assuming that all U5f electrons are itinerant. In contrast, the band structures of localized U5f compounds such as UPd3 and UO2 are essentially explained by the localized model that treats U5f electrons as localized core states. In regards to heavy fermion U-based compounds such as the hidden-order compound URu2Si2, their electronic structures exhibit complex behaviors. Their overall band structures are generally well-explained by the band-structure calculation, whereas the states in the vicinity of EF show some deviations due to electron correlation effects. Furthermore, the electronic structures of URu2Si2 in the paramagnetic and hidden-order phases are summarized based on various ARPES studies. The present status of the field as well as possible future directions are also discussed.
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Affiliation(s)
- Shin-ichi Fujimori
- Condensed Matter Science Division, Japan Atomic Energy Agency, Hyogo 679-5148, Japan
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He Y, Vishik IM, Yi M, Yang S, Liu Z, Lee JJ, Chen S, Rebec SN, Leuenberger D, Zong A, Jefferson CM, Moore RG, Kirchmann PS, Merriam AJ, Shen ZX. Invited Article: High resolution angle resolved photoemission with tabletop 11 eV laser. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:011301. [PMID: 26827301 DOI: 10.1063/1.4939759] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We developed a table-top vacuum ultraviolet (VUV) laser with 113.778 nm wavelength (10.897 eV) and demonstrated its viability as a photon source for high resolution angle-resolved photoemission spectroscopy (ARPES). This sub-nanosecond pulsed VUV laser operates at a repetition rate of 10 MHz, provides a flux of 2 × 10(12) photons/s, and enables photoemission with energy and momentum resolutions better than 2 meV and 0.012 Å(-1), respectively. Space-charge induced energy shifts and spectral broadenings can be reduced below 2 meV. The setup reaches electron momenta up to 1.2 Å(-1), granting full access to the first Brillouin zone of most materials. Control over the linear polarization, repetition rate, and photon flux of the VUV source facilitates ARPES investigations of a broad range of quantum materials, bridging the application gap between contemporary low energy laser-based ARPES and synchrotron-based ARPES. We describe the principles and operational characteristics of this source and showcase its performance for rare earth metal tritellurides, high temperature cuprate superconductors, and iron-based superconductors.
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Affiliation(s)
- Yu He
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Inna M Vishik
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Ming Yi
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Shuolong Yang
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Zhongkai Liu
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - James J Lee
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Sudi Chen
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Slavko N Rebec
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Dominik Leuenberger
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Alfred Zong
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | | | - Robert G Moore
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Patrick S Kirchmann
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Andrew J Merriam
- Lumeras LLC, 207 McPherson St, Santa Cruz, California 95060, USA
| | - Zhi-Xun Shen
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
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Richard P, Qian T, Ding H. ARPES measurements of the superconducting gap of Fe-based superconductors and their implications to the pairing mechanism. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:293203. [PMID: 26153847 DOI: 10.1088/0953-8984/27/29/293203] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Its direct momentum sensitivity confers to angle-resolved photoemission spectroscopy (ARPES) a unique perspective in investigating the superconducting gap of multi-band systems. In this review we discuss ARPES studies on the superconducting gap of high-temperature Fe-based superconductors. We show that while Fermi-surface-driven pairing mechanisms fail to provide a universal scheme for the Fe-based superconductors, theoretical approaches based on short-range interactions lead to a more robust and universal description of superconductivity in these materials. Our findings are also discussed in the broader context of unconventional superconductivity.
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Affiliation(s)
- P Richard
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China. Collaborative Innovation Center of Quantum Matter, Beijing, People's Republic of China
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Shoman T, Takayama A, Sato T, Souma S, Takahashi T, Oguchi T, Segawa K, Ando Y. Topological proximity effect in a topological insulator hybrid. Nat Commun 2015; 6:6547. [DOI: 10.1038/ncomms7547] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 02/06/2015] [Indexed: 11/09/2022] Open
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Jiang R, Mou D, Wu Y, Huang L, McMillen CD, Kolis J, Giesber HG, Egan JJ, Kaminski A. Tunable vacuum ultraviolet laser based spectrometer for angle resolved photoemission spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:033902. [PMID: 24689595 DOI: 10.1063/1.4867517] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We have developed an angle-resolved photoemission spectrometer with tunable vacuum ultraviolet laser as a photon source. The photon source is based on the fourth harmonic generation of a near IR beam from a Ti:sapphire laser pumped by a CW green laser and tunable between 5.3 eV and 7 eV. The most important part of the set-up is a compact, vacuum enclosed fourth harmonic generator based on potassium beryllium fluoroborate crystals, grown hydrothermally in the US. This source can deliver a photon flux of over 10(14) photon/s. We demonstrate that this energy range is sufficient to measure the k(z) dispersion in an iron arsenic high temperature superconductor, which was previously only possible at synchrotron facilities.
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Affiliation(s)
- Rui Jiang
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
| | - Daixiang Mou
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
| | - Yun Wu
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
| | - Lunan Huang
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
| | - Colin D McMillen
- Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA
| | - Joseph Kolis
- Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA
| | - Henry G Giesber
- Advanced Photonic Crystals LLC, Fort Mill, South Carolina 29708, USA
| | - John J Egan
- Advanced Photonic Crystals LLC, Fort Mill, South Carolina 29708, USA
| | - Adam Kaminski
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
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Albert DR, Proctor DL, Davis HF. High-intensity coherent vacuum ultraviolet source using unfocussed commercial dye lasers. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:063104. [PMID: 23822330 DOI: 10.1063/1.4806801] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Using two or three commercial pulsed nanosecond dye lasers pumped by a single 30 Hz Nd:YAG laser, generation of 0.10 mJ pulses at 125 nm (6 × 10(13) photons∕pulse) has been demonstrated by resonance enhanced four-wave mixing of collimated (unfocussed) laser beams in mercury (Hg) vapor. Phase matching at various vacuum ultraviolet (VUV) wavelengths is achieved by tuning one laser in the vicinity of the 6 (1)S0 → 6 (3)P1 resonance near 253.1 nm. A number of different mixing schemes are characterized. Our observations using broadband lasers (~0.15 cm(-1) bandwidths) are compared to previous calculations pertaining to four-wave mixing of low intensity narrowband laser beams. Prospects for further increases in pulse energies are discussed. We find that VUV tuning curves and intensities are in good agreement with theoretical predictions. The utility of the VUV light source is demonstrated by "soft universal" single-photon VUV ionization in crossed molecular beam studies and for generation of light at 130.2 nm for oxygen atom Rydberg time-of-flight experiments.
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Affiliation(s)
- Daniel R Albert
- Baker Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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Albert DR, Davis HF. Studies of bimolecular reaction dynamics using pulsed high-intensity vacuum-ultraviolet lasers for photoionization detection. Phys Chem Chem Phys 2013; 15:14566-80. [DOI: 10.1039/c3cp51930a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Takayama A, Sato T, Souma S, Oguchi T, Takahashi T. Tunable spin polarization in bismuth ultrathin film on Si(111). NANO LETTERS 2012; 12:1776-1779. [PMID: 22448971 DOI: 10.1021/nl2035018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We performed a spin- and angle-resolved photoemission spectroscopy of bismuth ultrathin film on Si(111) with various film thickness d. We found that the spin polarization of spin-split Rashba surface states near the Brillouin-zone boundary, which is high (0.7) at d = 40 BL (bilayers), is gradually reduced on decreasing d and almost vanishes at d = 8 BL. This finding provides a novel method to generate spin-polarized electrons with tunable spin-polarization.
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Affiliation(s)
- Akari Takayama
- Department of Physics, Tohoku University, Sendai 980-8578, Japan.
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11
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Tunable Dirac cone in the topological insulator Bi2-xSbxTe3-ySey. Nat Commun 2012; 3:636. [PMID: 22273674 DOI: 10.1038/ncomms1639] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 12/09/2011] [Indexed: 12/24/2022] Open
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12
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Souma S, Kosaka K, Sato T, Komatsu M, Takayama A, Takahashi T, Kriener M, Segawa K, Ando Y. Direct measurement of the out-of-plane spin texture in the Dirac-cone surface state of a topological insulator. PHYSICAL REVIEW LETTERS 2011; 106:216803. [PMID: 21699328 DOI: 10.1103/physrevlett.106.216803] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 04/27/2011] [Indexed: 05/31/2023]
Abstract
We have performed spin- and angle-resolved photoemission spectroscopy of Bi(2)Te(3) and present the first direct evidence for the existence of the out-of-plane spin component on the surface state of a topological insulator. We found that the magnitude of the out-of-plane spin polarization on a hexagonally deformed Fermi surface of Bi(2)Te(3) reaches maximally 25% of the in-plane counterpart, while such a sizable out-of-plane spin component does not exist in the more circular Fermi surface of TlBiSe(2), indicating that the hexagonal deformation of the Fermi surface is responsible for the deviation from the ideal helical spin texture. The observed out-of-plane polarization is much smaller than that expected from the existing theory, suggesting that an additional ingredient is necessary for correctly understanding the surface spin polarization in Bi(2)Te(3).
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Affiliation(s)
- S Souma
- WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
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Takayama A, Sato T, Souma S, Takahashi T. Giant out-of-plane spin component and the asymmetry of spin polarization in surface Rashba states of bismuth thin film. PHYSICAL REVIEW LETTERS 2011; 106:166401. [PMID: 21599390 DOI: 10.1103/physrevlett.106.166401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Indexed: 05/30/2023]
Abstract
We have performed high-resolution spin- and angle-resolved photoemission spectroscopy of bismuth thin film on Si(111) to investigate the spin structure of surface states. Unlike the conventional Rashba splitting, the magnitude of the in-plane spin polarization is asymmetric between the two elongated surface hole pockets across the zone center. Moreover, we uncovered a giant out-of-plane spin polarization as large as the in-plane counterpart which switches the sign across the Γ-M line. We discuss the present finding in terms of the symmetry breaking and the many-body effects.
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Affiliation(s)
- A Takayama
- Department of Physics, Tohoku University, Sendai, Japan
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Suga S, Sekiyama A, Funabashi G, Yamaguchi J, Kimura M, Tsujibayashi M, Uyama T, Sugiyama H, Tomida Y, Kuwahara G, Kitayama S, Fukushima K, Kimura K, Yokoi T, Murakami K, Fujiwara H, Saitoh Y, Plucinski L, Schneider CM. High resolution, low hν photoelectron spectroscopy with the use of a microwave excited rare gas lamp and ionic crystal filters. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:105111. [PMID: 21034123 DOI: 10.1063/1.3488367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The need for not only bulk sensitive but also extremely high resolution photoelectron spectroscopy for studying detailed electronic structures of strongly correlated electron systems is growing rapidly. Moreover, easy access to such a capability in one's own laboratory is desirable. Demonstrated here is the performance of a microwave excited rare gas (Xe, Kr, and Ar) lamp combined with ionic crystal filters (sapphire, CaF(2), and LiF), which can supply three strong lines near the photon energy of hnyu hν=8.4, 10.0, and 11.6 eV, with the hν resolution of better than 600 μeV for photoelectron spectroscopy. Its performance is demonstrated on some materials by means of both angle-integrated and angle-resolved measurements.
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Affiliation(s)
- S Suga
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
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15
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Sato T, Segawa K, Guo H, Sugawara K, Souma S, Takahashi T, Ando Y. Direct evidence for the dirac-cone topological surface states in the ternary chalcogenide TlBiSe₂. PHYSICAL REVIEW LETTERS 2010; 105:136802. [PMID: 21230796 DOI: 10.1103/physrevlett.105.136802] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2010] [Indexed: 05/30/2023]
Abstract
We have performed angle-resolved photoemission spectroscopy on TlBiSe₂, which is a member of the ternary chalcogenides theoretically proposed as candidates for a new class of three-dimensional topological insulators. We found direct evidence for a nontrivial surface metallic state showing an "X"-shaped energy dispersion within the bulk-band gap. The present result unambiguously establishes that TlBiSe₂ is a strong topological insulator with a single Dirac cone at the Brillouin-zone center. The observed bulk-band gap of 0.35 eV is the largest among known topological insulators, making TlBiSe₂ the most promising material for studying room-temperature topological phenomena.
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Affiliation(s)
- Takafumi Sato
- Department of Physics, Tohoku University, Sendai 980-8578, Japan
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Souma S, Takayama A, Sugawara K, Sato T, Takahashi T. Ultrahigh-resolution spin-resolved photoemission spectrometer with a mini Mott detector. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:095101. [PMID: 20887002 DOI: 10.1063/1.3480542] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We have developed an ultrahigh-resolution spin-resolved photoemission spectrometer with a highly efficient mini Mott detector and an intense xenon plasma discharge lamp. The spectrometer achieves the energy resolutions of 0.9 and 8 meV for non-spin-resolved and spin-resolved modes, respectively. Three-dimensional spin-polarization is determined by using a 90° electron deflector situated before the Mott detector. The performance of spectrometer is demonstrated by observation of a clear Rashba splitting of the Bi(111) surface states.
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Affiliation(s)
- S Souma
- WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
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17
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Offi F, Iacobucci S, Petaccia L, Gorovikov S, Vilmercati P, Rizzo A, Ruocco A, Goldoni A, Stefani G, Panaccione G. The attenuation length of low energy electrons in Yb. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:305002. [PMID: 21399353 DOI: 10.1088/0953-8984/22/30/305002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Photoelectron emission spectra in a photon energy range between 7.5 and 21 eV are measured for in situ grown polycrystalline Yb films. By comparing bulk and surface core level shifted 4f components we give an estimation of the effective attenuation length (EAL) for low energy (6-20 eV) electrons in Yb, establishing a moderate increase of the EAL upon electron energy decrease. The experimental EAL data are found to be a factor of four smaller than those predicted from the so-called 'universal curve'.
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Affiliation(s)
- F Offi
- CNISM and Dipartimento di Fisica, Università Roma Tre, Rome, Italy.
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18
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Kimura SI, Ito T, Sakai M, Nakamura E, Kondo N, Horigome T, Hayashi K, Hosaka M, Katoh M, Goto T, Ejima T, Soda K. SAMRAI: a novel variably polarized angle-resolved photoemission beamline in the VUV region at UVSOR-II. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:053104. [PMID: 20515121 DOI: 10.1063/1.3425778] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A novel variably polarized angle-resolved photoemission spectroscopy beamline in the vacuum-ultraviolet (VUV) region has been installed at the UVSOR-II 750 MeV synchrotron light source. The beamline is equipped with a 3 m long APPLE-II type undulator with horizontally/vertically linear and right/left circular polarizations, a 10 m Wadsworth type monochromator covering a photon energy range of 6-43 eV, and a 200 mm radius hemispherical photoelectron analyzer with an electron lens of a +/-18 degrees acceptance angle. Due to the low emittance of the UVSOR-II storage ring, the light source is regarded as an entrance slit, and the undulator light is directly led to a grating by two plane mirrors in the monochromator while maintaining a balance between high-energy resolution and high photon flux. The energy resolving power (hnu/Deltahnu) and photon flux of the monochromator are typically 1 x 10(4) and 10(12) photons/s, respectively, with a 100 microm exit slit. The beamline is used for angle-resolved photoemission spectroscopy with an energy resolution of a few meV covering the UV-to-VUV energy range.
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Affiliation(s)
- Shin-Ichi Kimura
- UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan.
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Nakayama K, Sato T, Sekiba Y, Terashima K, Richard P, Takahashi T, Kudo K, Okumura N, Sasaki T, Kobayashi N. Evolution of a pairing-induced pseudogap from the superconducting gap of (Bi,Pb)2Sr2CuO6. PHYSICAL REVIEW LETTERS 2009; 102:227006. [PMID: 19658895 DOI: 10.1103/physrevlett.102.227006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Indexed: 05/28/2023]
Abstract
We have performed an ultrahigh-resolution angle-resolved photoemission spectroscopy study of slightly overdoped (Bi,Pb)2Sr2CuO6 to elucidate the origin of the pseudogap. By using a newly developed xenon-plasma light source, we determined the comprehensive momentum and temperature dependencies of the superconducting gap and the pseudogap. We found that the antinodal pseudogap persists far above the superconducting transition temperature and is smoothly connected to the nodal gap. The characteristic temperature of the pseudogap scales well with the superconducting gap size irrespective of the momentum location. The present experimental results point to the pairing origin of the pseudogap.
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Affiliation(s)
- K Nakayama
- Department of Physics, Tohoku University, Sendai 980-8578, Japan
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Ma JH, Pan ZH, Niestemski FC, Neupane M, Xu YM, Richard P, Nakayama K, Sato T, Takahashi T, Luo HQ, Fang L, Wen HH, Wang Z, Ding H, Madhavan V. Coexistence of competing orders with two energy gaps in real and momentum space in the high temperature superconductor Bi_{2}Sr_{2-x}La_{x}CuO_{6+delta}. PHYSICAL REVIEW LETTERS 2008; 101:207002. [PMID: 19113369 DOI: 10.1103/physrevlett.101.207002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Indexed: 05/27/2023]
Abstract
Through a combined scanning tunneling microscopy and angle-resolved photoemission spectroscopy study, we report the observation of two distinct gaps (a small and a large gap) that coexist both in real space and in the antinodal region of momentum space, below the superconducting transition temperature (T_{c}) of Bi_{2}Sr_{2-x}La_{x}CuO_{6+delta}. We show that the small gap is associated with superconductivity. The large-gap persists above T_{c}, and seems linked to observed charge ordering. We find a strong correlation between the large and small gaps suggesting that they are affected by similar physical processes.
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Affiliation(s)
- J-H Ma
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
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