1
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Tkach O, Chernov S, Babenkov S, Lytvynenko Y, Fedchenko O, Medjanik K, Vasilyev D, Gloskowskii A, Schlueter C, Elmers HJ, Schönhense G. Asymmetric electrostatic dodecapole: compact bandpass filter with low aberrations for momentum microscopy. JOURNAL OF SYNCHROTRON RADIATION 2024; 31:829-840. [PMID: 38900457 PMCID: PMC11226149 DOI: 10.1107/s1600577524003540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 04/19/2024] [Indexed: 06/21/2024]
Abstract
Imaging energy filters in photoelectron microscopes and momentum microscopes use spherical fields with deflection angles of 90°, 180° and even 2 × 180°. These instruments are optimized for high energy resolution, and exhibit image aberrations when operated in high transmission mode at medium energy resolution. Here, a new approach is presented for bandpass-filtered imaging in real or reciprocal space using an electrostatic dodecapole with an asymmetric electrode array. In addition to energy-dispersive beam deflection, this multipole allows aberration correction up to the third order. Here, its use is described as a bandpass prefilter in a time-of-flight momentum microscope at the hard X-ray beamline P22 of PETRA III. The entire instrument is housed in a straight vacuum tube because the deflection angle is only 4° and the beam displacement in the filter is only ∼8 mm. The multipole is framed by transfer lenses in the entrance and exit branches. Two sets of 16 different-sized entrance and exit apertures on piezomotor-driven mounts allow selection of the desired bandpass. For pass energies between 100 and 1400 eV and slit widths between 0.5 and 4 mm, the transmitted kinetic energy intervals are between 10 eV and a few hundred electronvolts (full width at half-maximum). The filter eliminates all higher or lower energy signals outside the selected bandpass, significantly improving the signal-to-background ratio in the time-of-flight analyzer.
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Affiliation(s)
- O. Tkach
- Institut für PhysikJohannes Gutenberg-Universität Mainz55099MainzGermany
- Sumy State UniversityRymskogo-Korsakova 2Sumy40007Ukraine
| | - S. Chernov
- Deutsches Elektronen-Synchrotron DESY22607HamburgGermany
| | - S. Babenkov
- Institut für PhysikJohannes Gutenberg-Universität Mainz55099MainzGermany
| | - Y. Lytvynenko
- Institut für PhysikJohannes Gutenberg-Universität Mainz55099MainzGermany
- Institute of Magnetism of the NAS and MES of UkraineKyiv03142Ukraine
| | - O. Fedchenko
- Institut für PhysikJohannes Gutenberg-Universität Mainz55099MainzGermany
| | - K. Medjanik
- Institut für PhysikJohannes Gutenberg-Universität Mainz55099MainzGermany
| | - D. Vasilyev
- Institut für PhysikJohannes Gutenberg-Universität Mainz55099MainzGermany
| | - A. Gloskowskii
- Deutsches Elektronen-Synchrotron DESY22607HamburgGermany
| | - C. Schlueter
- Deutsches Elektronen-Synchrotron DESY22607HamburgGermany
| | - H.-J. Elmers
- Institut für PhysikJohannes Gutenberg-Universität Mainz55099MainzGermany
| | - G. Schönhense
- Institut für PhysikJohannes Gutenberg-Universität Mainz55099MainzGermany
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2
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Hagiwara K, Nakamura E, Makita S, Suga S, Tanaka SI, Kera S, Matsui F. Development of dual-beamline photoelectron momentum microscopy for valence orbital analysis. JOURNAL OF SYNCHROTRON RADIATION 2024; 31:540-546. [PMID: 38619289 DOI: 10.1107/s1600577524002406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 03/12/2024] [Indexed: 04/16/2024]
Abstract
The soft X-ray photoelectron momentum microscopy (PMM) experimental station at the UVSOR Synchrotron Facility has been recently upgraded by additionally guiding vacuum ultraviolet (VUV) light in a normal-incidence configuration. PMM offers a very powerful tool for comprehensive electronic structure analyses in real and momentum spaces. In this work, a VUV beam with variable polarization in the normal-incidence geometry was obtained at the same sample position as the soft X-ray beam from BL6U by branching the VUV beamline BL7U. The valence electronic structure of the Au(111) surface was measured using horizontal and vertical linearly polarized (s-polarized) light excitations from BL7U in addition to horizontal linearly polarized (p-polarized) light excitations from BL6U. Such highly symmetric photoemission geometry with normal incidence offers direct access to atomic orbital information via photon polarization-dependent transition-matrix-element analysis.
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Affiliation(s)
- Kenta Hagiwara
- UVSOR Synchrotron Facility, Institute for Molecular Science, NishigoNaka 38, Myodaiji, Okazaki 444-8585, Japan
| | - Eiken Nakamura
- UVSOR Synchrotron Facility, Institute for Molecular Science, NishigoNaka 38, Myodaiji, Okazaki 444-8585, Japan
| | - Seiji Makita
- UVSOR Synchrotron Facility, Institute for Molecular Science, NishigoNaka 38, Myodaiji, Okazaki 444-8585, Japan
| | - Shigemasa Suga
- SANKEN, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | | | - Satoshi Kera
- UVSOR Synchrotron Facility, Institute for Molecular Science, NishigoNaka 38, Myodaiji, Okazaki 444-8585, Japan
| | - Fumihiko Matsui
- UVSOR Synchrotron Facility, Institute for Molecular Science, NishigoNaka 38, Myodaiji, Okazaki 444-8585, Japan
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3
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Iwata T, Kousa T, Nishioka Y, Ohwada K, Sumida K, Annese E, Kakoki M, Kuroda K, Iwasawa H, Arita M, Kumar S, Kimura A, Miyamoto K, Okuda T. Laser-based angle-resolved photoemission spectroscopy with micrometer spatial resolution and detection of three-dimensional spin vector. Sci Rep 2024; 14:127. [PMID: 38177136 PMCID: PMC10766951 DOI: 10.1038/s41598-023-47719-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 11/17/2023] [Indexed: 01/06/2024] Open
Abstract
We have developed a state-of-the-art apparatus for laser-based spin- and angle-resolved photoemission spectroscopy with micrometer spatial resolution (µ-SARPES). This equipment is realized by the combination of a high-resolution photoelectron spectrometer, a 6 eV laser with high photon flux that is focused down to a few micrometers, a high-precision sample stage control system, and a double very-low-energy-electron-diffraction spin detector. The setup achieves an energy resolution of 1.5 (5.5) meV without (with) the spin detection mode, compatible with a spatial resolution better than 10 µm. This enables us to probe both spatially-resolved electronic structures and vector information of spin polarization in three dimensions. The performance of µ-SARPES apparatus is demonstrated by presenting ARPES and SARPES results from topological insulators and Au photolithography patterns on a Si (001) substrate.
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Affiliation(s)
- Takuma Iwata
- Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan
- International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM2), Hiroshima University, Higashi-hiroshima, 739-8526, Japan
| | - T Kousa
- Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan
| | - Y Nishioka
- Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan
| | - K Ohwada
- Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan
| | - K Sumida
- Materials Sciences Research Center, Japan Atomic Energy Agency, Sayo-gun, Hyogo, 679-5148, Japan
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima, 739-0046, Japan
| | - E Annese
- Brazilian Center for Research in Physics, Rua Dr. Xavier Sigaud 150, Rio de Janeiro, RJ, 22290-180, Brazil
| | - M Kakoki
- Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan
| | - Kenta Kuroda
- Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan.
- International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM2), Hiroshima University, Higashi-hiroshima, 739-8526, Japan.
| | - H Iwasawa
- Institute for Advanced Synchrotron Light Source, National Institutes for Quantum Science and Technology, Sendai, 980-8579, Japan
- Synchrotron Radiation Research Center, National Institutes for Quantum Science and Technology, Hyogo, 679-5148, Japan
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima, 739-0046, Japan
| | - M Arita
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima, 739-0046, Japan
| | - S Kumar
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima, 739-0046, Japan
| | - A Kimura
- Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan
- International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM2), Hiroshima University, Higashi-hiroshima, 739-8526, Japan
| | - K Miyamoto
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima, 739-0046, Japan
| | - T Okuda
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima, 739-0046, Japan
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4
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Chuang TH, Hsu CC, Chiu WS, Jhuang JS, Yeh IC, Chen RS, Gwo S, Wei DH. Performance of a photoelectron momentum microscope in direct- and momentum-space imaging with ultraviolet photon sources. JOURNAL OF SYNCHROTRON RADIATION 2024; 31:195-201. [PMID: 38038695 PMCID: PMC10833436 DOI: 10.1107/s1600577523009761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 11/08/2023] [Indexed: 12/02/2023]
Abstract
The Photoelectron-Related Image and Nano-Spectroscopy (PRINS) endstation located at the Taiwan Photon Source beamline 27A2 houses a photoelectron momentum microscope capable of performing direct-space imaging, momentum-space imaging and photoemission spectroscopy with position sensitivity. Here, the performance of this microscope is demonstrated using two in-house photon sources - an Hg lamp and He(I) radiation - on a standard checkerboard-patterned specimen and an Au(111) single crystal, respectively. By analyzing the intensity profile of the edge of the Au patterns, the Rashba-splitting of the Au(111) Shockley surface state at 300 K, and the photoelectron intensity across the Fermi edge at 80 K, the spatial, momentum and energy resolution were estimated to be 50 nm, 0.0172 Å-1 and 26 meV, respectively. Additionally, it is shown that the band structures acquired in either constant energy contour mode or momentum-resolved photoemission spectroscopy mode were in close agreement.
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Affiliation(s)
- Tzu-Hung Chuang
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
| | - Chuan-Che Hsu
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
| | - Wei-Sheng Chiu
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, Taiwan
| | | | - I-Chun Yeh
- Department of Physics, National Tsing-Hua University, Hsinchu, Taiwan
| | - Ruei-San Chen
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, Taiwan
| | - Shanjr Gwo
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
- Department of Physics, National Tsing-Hua University, Hsinchu, Taiwan
| | - Der-Hsin Wei
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
- Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
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5
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Tan XL, Hagiwara K, Chen YJ, Schusser J, Cojocariu I, Baranowski D, Feyer V, Minár J, Schneider CM, Tusche C. Soft X-ray Fermi surface tomography of palladium and rhodium via momentum microscopy. Ultramicroscopy 2023; 253:113820. [PMID: 37586245 DOI: 10.1016/j.ultramic.2023.113820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 06/10/2023] [Accepted: 07/25/2023] [Indexed: 08/18/2023]
Abstract
Fermi surfaces of transition metals, which describe all thermodynamical and transport quantities of solids, often fail to be modeled by one-electron mean-field theory due to strong correlations among the valence electrons. In addition, relativistic spin-orbit coupling pronounced in heavier elements lifts the degeneracy of the energy bands and further modifies the Fermi surface. Palladium and rhodium, two 4d metals attributed to show significant spin-orbit coupling and electron correlations, are ideal for a systematic and fundamental study of the two fundamental physical phenomena and their interplay in the electronic structure. In this study, we explored the Fermi surface of the 4d noble metals palladium and rhodium obtained via high-resolution constant initial state momentum microscopy. The complete 3D-Fermi surfaces of palladium and rhodium were tomographically mapped using soft X-ray photon energies from 34 eV up to 660 eV. To fully capture the orbital angular momentum of states across the Fermi surface, the Fermi surface tomography was performed using p- and s- polarized light. Applicability and limitations of the nearly-free electron final state model in photoemission are discussed using a complex band structure model supported by experimental evidence. The significance of spin-orbit coupling and electron correlations across the Fermi surfaces will be discussed within the context of the photoemission results. State-of-the-art fully relativistic Korringa-Kohn-Rostoker (KKR) calculations within the one-step model of photoemission are used to support the experimental results.
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Affiliation(s)
- Xin Liang Tan
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany.
| | - Kenta Hagiwara
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Ying-Jiun Chen
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany; Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Jakub Schusser
- New Technologies Research Centre, University of West Bohemia, 30614, Pilsen, Czech Republic; Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, 97074, Würzburg, Germany
| | - Iulia Cojocariu
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany; Elettra - Sincrotrone Trieste S.C.p.A., S.S. 14 - km 163.5, 34149, Basovizza, Trieste, Italy
| | - Daniel Baranowski
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Vitaliy Feyer
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Ján Minár
- New Technologies Research Centre, University of West Bohemia, 30614, Pilsen, Czech Republic
| | - Claus M Schneider
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany; Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany; Department of Physics, University of California Davis, One Shields Ave., 95616 CA, Davis, USA
| | - Christian Tusche
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, 52425, Jülich, Germany; Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
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6
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Escher M, Weber NB, Kühn TJ, Patt M. 2D imaging spin-filter for NanoESCA based on Au/Ir(001) or Fe(001)-p(1×1)O. Ultramicroscopy 2023; 253:113814. [PMID: 37515931 DOI: 10.1016/j.ultramic.2023.113814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 06/30/2023] [Accepted: 07/12/2023] [Indexed: 07/31/2023]
Abstract
A two-dimensional imaging spin-filter for photo-emission electron microscopy is described. The spin-filter is capable of imaging the electron spin polarization of either real space or momentum space electron distributions. As a scattering target either Au/Ir(001) comes into use, where spin sensitivity results from using spin-orbit scattering or Fe(001)-p(1×1)O that exploits exchange interaction. Both scattering targets were characterized with respect to their working points and Sherman function in a separate setup. Spin-polarization images of secondary electrons from the magnetic domains of a poly-crystalline iron sample are shown using both scattering targets. Images with a spin-filter using Au/Ir(001) show more than 104 discrete detection channels which increases the effective two-dimensional figure-of-merit (FoM) of this spin-filter by four orders of magnitude compared to single-channel spin detectors. Using the exchange scattering target two spin-components have been imaged for the first time. A method to detect all three spin-components is also outlined.
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Affiliation(s)
- M Escher
- Focus GmbH, 65510 Hünstetten-Kesselbach, Germany.
| | - N B Weber
- Focus GmbH, 65510 Hünstetten-Kesselbach, Germany
| | - T-J Kühn
- Focus GmbH, 65510 Hünstetten-Kesselbach, Germany
| | - M Patt
- Focus GmbH, 65510 Hünstetten-Kesselbach, Germany
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7
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Tebyani A, Schramm S, Hesselberth M, Boltje D, Jobst J, Tromp R, van der Molen SJ. Low energy electron microscopy at cryogenic temperatures. Ultramicroscopy 2023; 253:113815. [PMID: 37480839 DOI: 10.1016/j.ultramic.2023.113815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 06/16/2023] [Accepted: 07/12/2023] [Indexed: 07/24/2023]
Abstract
We describe a cryogenic sample chamber for low energy electron microscopy (LEEM), and present first experimental results. Modifications to our IBM/SPECS aberration-corrected LEEM instrument are presented first. These include incorporation of mechanisms for cooling the sample and its surroundings, and reduction of various sources of heat load. Using both liquid nitrogen and liquid helium, we have reached sample temperatures down to about 15 K. We also present first results for low-temperature LEEM, obtained on a three-monolayer pentacene film. Specifically, we observe a reduction of the electron beam irradiation damage cross-section at 15 eV by more than a factor of five upon cooling from 300 K down to 52 K. We also observe changes in the LEEM-IV spectra of the sample upon cooling, and discuss possible causes.
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Affiliation(s)
- Arash Tebyani
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands
| | - Sebastian Schramm
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands
| | - Marcel Hesselberth
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands
| | - Daan Boltje
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands
| | - Johannes Jobst
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands
| | - Rudolf Tromp
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands; IBM T. J. Watson Research Center, 1101 Kitchawan Road, P.O. Box 218, Yorktown Heights, New York, New York 10598, USA
| | - Sense Jan van der Molen
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands.
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8
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Neuhaus A, Dreher P, Schütz F, Marchetto H, Franz T, Meyer zu Heringdorf F. Angle-resolved photoelectron spectroscopy in a low-energy electron microscope. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2023; 10:064304. [PMID: 38162194 PMCID: PMC10757648 DOI: 10.1063/4.0000216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 12/05/2023] [Indexed: 01/03/2024]
Abstract
Spectroscopic photoemission microscopy is a well-established method to investigate the electronic structure of surfaces. In modern photoemission microscopes, the electron optics allow imaging of the image plane, momentum plane, or dispersive plane, depending on the lens setting. Furthermore, apertures allow filtering of energy-, real-, and momentum space. Here, we describe how a standard spectroscopic and low-energy electron microscope can be equipped with an additional slit at the entrance of the already present hemispherical analyzer to enable an angle- and energy-resolved photoemission mode with micrometer spatial selectivity. We apply a photogrammetric calibration to correct for image distortions of the projective system behind the analyzer and present spectra recorded on Au(111) as a benchmark. Our approach makes data acquisition in energy-momentum space more efficient, which is a necessity for laser-based pump-probe photoemission microscopy with femtosecond time resolution.
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Affiliation(s)
- Alexander Neuhaus
- Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47048 Duisburg, Germany
| | - Pascal Dreher
- Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47048 Duisburg, Germany
| | - Florian Schütz
- ELMITEC Elektronenmikroskopie GmbH, 38678 Clausthal-Zellerfeld, Germany
| | - Helder Marchetto
- ELMITEC Elektronenmikroskopie GmbH, 38678 Clausthal-Zellerfeld, Germany
| | - Torsten Franz
- ELMITEC Elektronenmikroskopie GmbH, 38678 Clausthal-Zellerfeld, Germany
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9
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Røst HI, Cooil SP, Åsland AC, Hu J, Ali A, Taniguchi T, Watanabe K, Belle BD, Holst B, Sadowski JT, Mazzola F, Wells JW. Phonon-Mediated Quasiparticle Lifetime Renormalizations in Few-Layer Hexagonal Boron Nitride. NANO LETTERS 2023; 23:7539-7545. [PMID: 37561835 PMCID: PMC10450811 DOI: 10.1021/acs.nanolett.3c02086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 07/28/2023] [Indexed: 08/12/2023]
Abstract
Understanding the collective behavior of the quasiparticles in solid-state systems underpins the field of nonvolatile electronics, including the opportunity to control many-body effects for well-desired physical phenomena and their applications. Hexagonal boron nitride (hBN) is a wide-energy-bandgap semiconductor, showing immense potential as a platform for low-dimensional device heterostructures. It is an inert dielectric used for gated devices, having a negligible orbital hybridization when placed in contact with other systems. Despite its inertness, we discover a large electron mass enhancement in few-layer hBN affecting the lifetime of the π-band states. We show that the renormalization is phonon-mediated and consistent with both single- and multiple-phonon scattering events. Our findings thus unveil a so-far unknown many-body state in a wide-bandgap insulator, having important implications for devices using hBN as one of their building blocks.
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Affiliation(s)
- Håkon I. Røst
- Department
of Physics and Technology, University of
Bergen, Allégaten 55, 5007 Bergen, Norway
- Department
of Physics, Norwegian University of Science
and Technology (NTNU), NO-7491 Trondheim, Norway
| | - Simon P. Cooil
- Department
of Physics and Centre for Materials Science and Nanotechnology, University of Oslo (UiO), Oslo 0318, Norway
| | - Anna Cecilie Åsland
- Department
of Physics, Norwegian University of Science
and Technology (NTNU), NO-7491 Trondheim, Norway
| | - Jinbang Hu
- Department
of Physics, Norwegian University of Science
and Technology (NTNU), NO-7491 Trondheim, Norway
| | - Ayaz Ali
- Department
of Smart Sensor Systems, SINTEF DIGITAL, Oslo 0373, Norway
- Department
of Electronic Engineering, Faculty of Engineering & Technology, University of Sindh, Jamshoro 76080, Pakistan
| | - Takashi Taniguchi
- International
Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- Research
Center for Functional Materials, National
Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Branson D. Belle
- Department
of Smart Sensor Systems, SINTEF DIGITAL, Oslo 0373, Norway
| | - Bodil Holst
- Department
of Physics and Technology, University of
Bergen, Allégaten 55, 5007 Bergen, Norway
| | - Jerzy T. Sadowski
- Center
for Functional Nanomaterials, Brookhaven
National Laboratory, Upton, New York 11973, United States
| | - Federico Mazzola
- Department
of Molecular Sciences and Nanosystems, Ca’
Foscari University of Venice, 30172 Venice, Italy
- Istituto
Officina dei Materiali, Consiglio Nazionale
delle Ricerche, Trieste I-34149, Italy
| | - Justin W. Wells
- Department
of Physics, Norwegian University of Science
and Technology (NTNU), NO-7491 Trondheim, Norway
- Department
of Physics and Centre for Materials Science and Nanotechnology, University of Oslo (UiO), Oslo 0318, Norway
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10
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Heider T, Bihlmayer G, Schusser J, Reinert F, Minár J, Blügel S, Schneider CM, Plucinski L. Geometry-Induced Spin Filtering in Photoemission Maps from WTe_{2} Surface States. PHYSICAL REVIEW LETTERS 2023; 130:146401. [PMID: 37084452 DOI: 10.1103/physrevlett.130.146401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/22/2022] [Accepted: 02/24/2023] [Indexed: 05/03/2023]
Abstract
We demonstrate that an important quantum material WTe_{2} exhibits a new type of geometry-induced spin filtering effect in photoemission, stemming from low symmetry that is responsible for its exotic transport properties. Through the laser-driven spin-polarized angle-resolved photoemission Fermi surface mapping, we showcase highly asymmetric spin textures of electrons photoemitted from the surface states of WTe_{2}. Such asymmetries are not present in the initial state spin textures, which are bound by the time-reversal and crystal lattice mirror plane symmetries. The findings are reproduced qualitatively by theoretical modeling within the one-step model photoemission formalism. The effect could be understood within the free-electron final state model as an interference due to emission from different atomic sites. The observed effect is a manifestation of time-reversal symmetry breaking of the initial state in the photoemission process, and as such it cannot be eliminated, but only its magnitude influenced, by special experimental geometries.
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Affiliation(s)
- Tristan Heider
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Gustav Bihlmayer
- Peter Grünberg Institut (PGI-1) and Institute for Advanced Simulation (IAS-1), Forschungszentrum Jülich and JARA, 52428 Jülich, Germany
| | - Jakub Schusser
- New Technologies-Research Center, University of West Bohemia, 30614 Pilsen, Czech Republic
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, 97070 Würzburg, Germany
| | - Friedrich Reinert
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, 97070 Würzburg, Germany
| | - Jan Minár
- New Technologies-Research Center, University of West Bohemia, 30614 Pilsen, Czech Republic
| | - Stefan Blügel
- Peter Grünberg Institut (PGI-1) and Institute for Advanced Simulation (IAS-1), Forschungszentrum Jülich and JARA, 52428 Jülich, Germany
| | - Claus M Schneider
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
- Fakultät für Physik, Universität Duisburg-Essen, 47048 Duisburg, Germany
- Physics Department, University of California, Davis, California 95616, USA
| | - Lukasz Plucinski
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
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11
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Donath M, Schöttke F, Krüger P. Comment on "Spin- and angle-resolved inverse photoemission setup with spin orientation independent from electron incidence angle" [Rev. Sci. Instrum. 93, 093904 (2022)]. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:037101. [PMID: 37012808 DOI: 10.1063/5.0131463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 12/16/2022] [Indexed: 06/19/2023]
Abstract
The paper under discussion promises a spin- and angle-resolved inverse-photoemission (IPE) setup, where the spin-polarization direction of the electron beam used for excitation "can be tuned to any preferred direction" while "preserving the parallel beam condition." We support the idea to improve IPE setups by introducing a three-dimensional spin-polarization rotator, but we put the presented results to the test by comparing them with the literature results obtained by existing setups. Based on this comparison, we conclude that the presented proof-of-principle experiments miss the target in several aspects. Most importantly, the key experiment of tuning the spin-polarization direction under otherwise allegedly identical experimental conditions causes changes in the IPE spectra that are in conflict with existing experimental results and basic quantum-mechanical considerations. We propose experimental test measurements to identify and overcome the shortcomings.
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Affiliation(s)
- Markus Donath
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
| | - Fabian Schöttke
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
| | - Peter Krüger
- Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
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12
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Yannai M, Dahan R, Gorlach A, Adiv Y, Wang K, Madan I, Gargiulo S, Barantani F, Dias EJC, Vanacore GM, Rivera N, Carbone F, García de Abajo FJ, Kaminer I. Ultrafast Electron Microscopy of Nanoscale Charge Dynamics in Semiconductors. ACS NANO 2023; 17:3645-3656. [PMID: 36736033 DOI: 10.1021/acsnano.2c10481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The ultrafast dynamics of charge carriers in solids plays a pivotal role in emerging optoelectronics, photonics, energy harvesting, and quantum technology applications. However, the investigation and direct visualization of such nonequilibrium phenomena remains as a long-standing challenge, owing to the nanometer-femtosecond spatiotemporal scales at which the charge carriers evolve. Here, we propose and demonstrate an interaction mechanism enabling nanoscale imaging of the femtosecond dynamics of charge carriers in solids. This imaging modality, which we name charge dynamics electron microscopy (CDEM), exploits the strong interaction of free-electron pulses with terahertz (THz) near fields produced by the moving charges in an ultrafast scanning transmission electron microscope. The measured free-electron energy at different spatiotemporal coordinates allows us to directly retrieve the THz near-field amplitude and phase, from which we reconstruct movies of the generated charges by comparison to microscopic theory. The CDEM technique thus allows us to investigate previously inaccessible spatiotemporal regimes of charge dynamics in solids, providing insight into the photo-Dember effect and showing oscillations of photogenerated electron-hole distributions inside a semiconductor. Our work facilitates the exploration of a wide range of previously inaccessible charge-transport phenomena in condensed matter using ultrafast electron microscopy.
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Affiliation(s)
- Michael Yannai
- Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Raphael Dahan
- Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Alexey Gorlach
- Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Yuval Adiv
- Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Kangpeng Wang
- Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Ivan Madan
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Station 6, Lausanne 1015, Switzerland
| | - Simone Gargiulo
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Station 6, Lausanne 1015, Switzerland
| | - Francesco Barantani
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Station 6, Lausanne 1015, Switzerland
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Eduardo J C Dias
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Giovanni Maria Vanacore
- Department of Materials Science, University of Milano-Bicocca, Via Cozzi 55, 20121 Milano, Italy
| | - Nicholas Rivera
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Fabrizio Carbone
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Station 6, Lausanne 1015, Switzerland
| | - F Javier García de Abajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona, Spain
| | - Ido Kaminer
- Technion - Israel Institute of Technology, Haifa 3200003, Israel
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13
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Spanning Fermi arcs in a two-dimensional magnet. Nat Commun 2022; 13:5309. [PMID: 36085323 PMCID: PMC9463448 DOI: 10.1038/s41467-022-32948-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 08/24/2022] [Indexed: 11/08/2022] Open
Abstract
The discovery of topological states of matter has led to a revolution in materials research. When external or intrinsic parameters break symmetries, global properties of topological materials change drastically. A paramount example is the emergence of Weyl nodes under broken inversion symmetry. While a rich variety of non-trivial quantum phases could in principle also originate from broken time-reversal symmetry, realizing systems that combine magnetism with complex topological properties is remarkably elusive. Here, we demonstrate that giant open Fermi arcs are created at the surface of ultrathin hybrid magnets where the Fermi-surface topology is substantially modified by hybridization with a heavy-metal substrate. The interplay between magnetism and topology allows us to control the shape and the location of the Fermi arcs by tuning the magnetization direction. The hybridization points in the Fermi surface can be attributed to a non-trivial mixed topology and induce hot-spots in the Berry curvature, dominating spin and charge transport as well as magneto-electric coupling effects. It has been predicted that elemental Iron, with low dimensionality, will be a topological metal hosting Weyl nodes. Here, Chen et al. grow iron on tungsten, a heavy metal with a strong spin-orbit interaction, and using momentum microscopy, show the emergence of giant open Fermi arcs which can be shaped by varying the magnetization of the iron.
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14
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Campos AF, Duret P, Cabaret S, Duden T, Tejeda A. Spin- and angle-resolved inverse photoemission setup with spin orientation independent from electron incidence angle. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:093904. [PMID: 36182468 DOI: 10.1063/5.0076088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 05/21/2022] [Indexed: 06/16/2023]
Abstract
A new spin- and angle-resolved inverse photoemission setup with a low-energy electron source is presented. The spin-polarized electron source, with a compact design, can decouple the spin polarization vector from the electron beam propagation vector, allowing one to explore any spin orientation at any wavevector in angle-resolved inverse photoemission. The beam polarization can be tuned to any preferred direction with a shielded electron optical system, preserving the parallel beam condition. We demonstrate the performances of the setup by measurements on Cu(001) and Au(111). We estimate the energy resolution of the overall system at room temperature to be ∼170 meV from kBTeff of a Cu(001) Fermi level, allowing a direct comparison to photoemission. The spin-resolved operation of the setup has been demonstrated by measuring the Rashba splitting of the Au(111) Shockley surface state. The effective polarization of the electron beam is P = 30% ± 3%, and the wavevector resolution is ΔkF ≲ 0.06 Å-1. Measurements on the Au(111) surface state demonstrate how the electron beam polarization direction can be tuned in the three spatial dimensions. The maximum of the spin asymmetry is reached when the electron beam polarization is aligned with the in-plane spin polarization of the Au(111) surface state.
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Affiliation(s)
- A F Campos
- Laboratoire de Physique des Solides, CNRS, Université Paris-Saclay, 91405 Orsay, France
| | - P Duret
- Laboratoire de Physique des Solides, CNRS, Université Paris-Saclay, 91405 Orsay, France
| | - S Cabaret
- Laboratoire de Physique des Solides, CNRS, Université Paris-Saclay, 91405 Orsay, France
| | - T Duden
- Constructive Solutions for Science and Technology, 33649 Bielefeld, Germany
| | - A Tejeda
- Laboratoire de Physique des Solides, CNRS, Université Paris-Saclay, 91405 Orsay, France
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15
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Formation of moiré interlayer excitons in space and time. Nature 2022; 608:499-503. [PMID: 35978130 DOI: 10.1038/s41586-022-04977-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 06/14/2022] [Indexed: 11/09/2022]
Abstract
Moiré superlattices in atomically thin van der Waals heterostructures hold great promise for extended control of electronic and valleytronic lifetimes1-7, the confinement of excitons in artificial moiré lattices8-13 and the formation of exotic quantum phases14-18. Such moiré-induced emergent phenomena are particularly strong for interlayer excitons, where the hole and the electron are localized in different layers of the heterostructure19,20. To exploit the full potential of correlated moiré and exciton physics, a thorough understanding of the ultrafast interlayer exciton formation process and the real-space wavefunction confinement is indispensable. Here we show that femtosecond photoemission momentum microscopy provides quantitative access to these key properties of the moiré interlayer excitons. First, we elucidate that interlayer excitons are dominantly formed through femtosecond exciton-phonon scattering and subsequent charge transfer at the interlayer-hybridized Σ valleys. Second, we show that interlayer excitons exhibit a momentum fingerprint that is a direct hallmark of the superlattice moiré modification. Third, we reconstruct the wavefunction distribution of the electronic part of the exciton and compare the size with the real-space moiré superlattice. Our work provides direct access to interlayer exciton formation dynamics in space and time and reveals opportunities to study correlated moiré and exciton physics for the future realization of exotic quantum phases of matter.
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16
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Karni O, Esin I, Dani KM. Through the Lens of a Momentum Microscope: Viewing Light-Induced Quantum Phenomena in 2D Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022:e2204120. [PMID: 35817468 DOI: 10.1002/adma.202204120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/23/2022] [Indexed: 06/15/2023]
Abstract
Van der Waals (vdW) materials at their 2D limit are diverse, flexible, and unique laboratories to study fundamental quantum phenomena and their future applications. Their novel properties rely on their pronounced Coulomb interactions, variety of crystal symmetries and spin-physics, and the ease of incorporation of different vdW materials to form sophisticated heterostructures. In particular, the excited state properties of many 2D semiconductors and semi-metals are relevant for their technological applications, particularly those that can be induced by light. In this paper, the recent advances made in studying out-of-equilibrium, light-induced, phenomena in these materials are reviewed using powerful, surface-sensitive, time-resolved photoemission-based techniques, with a particular emphasis on the emerging multi-dimensional photoemission spectroscopy technique of time-resolved momentum microscopy. The advances this technique has enabled in studying the nature and dynamics of occupied excited states in these materials are discussed. Then, the future research directions opened by these scientific and instrumental advancements are projected for studying the physics of 2D materials and the opportunities to engineer their band-structure and band-topology by laser fields.
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Affiliation(s)
- Ouri Karni
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Iliya Esin
- Department of Physics, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Keshav M Dani
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa, 904-0495, Japan
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17
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Shibuta M, Nakajima A. Spectroscopic imaging of photoexcited states at a polycrystalline copper metal surface via two-photon photoelectron emission microscopy. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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18
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Krivenkov M, Marchenko D, Sajedi M, Fedorov A, Clark OJ, Sánchez-Barriga J, Rienks EDL, Rader O, Varykhalov A. On the problem of Dirac cones in fullerenes on gold. NANOSCALE 2022; 14:9124-9133. [PMID: 35723255 DOI: 10.1039/d1nr07981f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Artificial graphene based on molecular networks enables the creation of novel 2D materials with unique electronic and topological properties. Landau quantization has been demonstrated by CO molecules arranged on the two-dimensional electron gas on Cu(111) and the observation of electron quantization may succeed based on the created gauge fields. Recently, it was reported that instead of individual manipulation of CO molecules, simple deposition of nonpolar C60 molecules on Cu(111) and Au(111) produces artificial graphene as evidenced by Dirac cones in photoemission spectroscopy. Here, we show that C60-induced Dirac cones on Au(111) have a different origin. We argue that those are related to umklapp diffraction of surface electronic bands of Au on the molecular grid of C60 in the final state of photoemission. We test this alternative explanation by precisely probing the dimensionality of the observed conical features in the photoemission spectra, by varying both the incident photon energy and the degree of charge doping via alkali adatoms. Using density functional theory calculations and spin-resolved photoemission we reveal the origin of the replicating Au(111) bands and resolve them as deep leaky surface resonances derived from the bulk Au sp-band residing at the boundary of its surface projection. We also discuss the manifold nature of these resonances which gives rise to an onion-like Fermi surface of Au(111).
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Affiliation(s)
- M Krivenkov
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - D Marchenko
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - M Sajedi
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - A Fedorov
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
- IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany
- Joint Laboratory 'Functional Quantum Materials' at BESSY II, 12489, Berlin, Germany
| | - O J Clark
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - J Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - E D L Rienks
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - O Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - A Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
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19
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Polyakov A, Mohseni K, Felici R, Tusche C, Chen YJ, Feyer V, Geck J, Ritschel T, Ernst A, Rubio-Zuazo J, Castro GR, Meyerheim HL, Parkin SSP. Fermi surface chirality induced in a TaSe 2 monosheet formed by a Ta/Bi 2Se 3 interface reaction. Nat Commun 2022; 13:2472. [PMID: 35513364 PMCID: PMC9072342 DOI: 10.1038/s41467-022-30093-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 04/14/2022] [Indexed: 11/09/2022] Open
Abstract
Spin-momentum locking in topological insulators and materials with Rashba-type interactions is an extremely attractive feature for novel spintronic devices and is therefore under intense investigation. Significant efforts are underway to identify new material systems with spin-momentum locking, but also to create heterostructures with new spintronic functionalities. In the present study we address both subjects and investigate a van der Waals-type heterostructure consisting of the topological insulator Bi2Se3 and a single Se-Ta-Se triple-layer (TL) of H-type TaSe2 grown by a method which exploits an interface reaction between the adsorbed metal and selenium. We then show, using surface x-ray diffraction, that the symmetry of the TaSe2-like TL is reduced from D3h to C3v resulting from a vertical atomic shift of the tantalum atom. Spin- and momentum-resolved photoemission indicates that, owing to the symmetry lowering, the states at the Fermi surface acquire an in-plane spin component forming a surface contour with a helical Rashba-like spin texture, which is coupled to the Dirac cone of the substrate. Our approach provides a route to realize chiral two-dimensional electron systems via interface engineering in van der Waals epitaxy that do not exist in the corresponding bulk materials. Current limitations of spintronics devices based on bulk topological materials stimulate the search for new materials and structures with interesting spin properties. Here the authors report a chiral spin texture around the Fermi level related to structural symmetry breaking in a TaSe2 layer grown on a Bi2Se3 surface.
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Affiliation(s)
- Andrey Polyakov
- Max-Planck-Institut für Mikrostukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Katayoon Mohseni
- Max-Planck-Institut für Mikrostukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Roberto Felici
- Consiglio Nazionale delle Ricerche - SPIN, Via del Politecnico, 1, Roma, 00133, Italy
| | - Christian Tusche
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany.,Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Ying-Jun Chen
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany.,Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Vitaly Feyer
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany.,Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Jochen Geck
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062, Dresden, Germany.,Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062, Dresden, Germany
| | - Tobias Ritschel
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062, Dresden, Germany
| | - Arthur Ernst
- Institut für Theoretische Physik, Johannes Kepler Universität, A 4040, Linz, Austria
| | - Juan Rubio-Zuazo
- SpLine, Spanish CRG BM25 Beamline at the ESRF (The European Synchrotron), F-38000, Grenoble, France
| | - German R Castro
- SpLine, Spanish CRG BM25 Beamline at the ESRF (The European Synchrotron), F-38000, Grenoble, France
| | - Holger L Meyerheim
- Max-Planck-Institut für Mikrostukturphysik, Weinberg 2, 06120, Halle, Germany.
| | - Stuart S P Parkin
- Max-Planck-Institut für Mikrostukturphysik, Weinberg 2, 06120, Halle, Germany
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20
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Kitamura M, Souma S, Honma A, Wakabayashi D, Tanaka H, Toyoshima A, Amemiya K, Kawakami T, Sugawara K, Nakayama K, Yoshimatsu K, Kumigashira H, Sato T, Horiba K. Development of a versatile micro-focused angle-resolved photoemission spectroscopy system with Kirkpatrick-Baez mirror optics. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:033906. [PMID: 35364976 DOI: 10.1063/5.0074393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
Angle-resolved photoemission spectroscopy using a micro-focused beam spot [micro-angle-resolved photoemission spectroscopy (ARPES)] is becoming a powerful tool to elucidate key electronic states of exotic quantum materials. We have developed a versatile micro-ARPES system based on the synchrotron radiation beam focused with a Kirkpatrick-Baez mirror optics. The mirrors are monolithically installed on a stage, which is driven with five-axis motion, and are vibrationally separated from the ARPES measurement system. Spatial mapping of the Au photolithography pattern on Si signifies the beam spot size of 10 µm (horizontal) × 12 µm (vertical) at the sample position, which is well suited to resolve the fine structure in local electronic states. Utilization of the micro-beam and the high precision sample motion system enables the accurate spatially resolved band-structure mapping, as demonstrated by the observation of a small band anomaly associated with tiny sample bending near the edge of a cleaved topological insulator single crystal.
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Affiliation(s)
- Miho Kitamura
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
| | - Seigo Souma
- Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan
| | - Asuka Honma
- Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Daisuke Wakabayashi
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
| | - Hirokazu Tanaka
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
| | - Akio Toyoshima
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
| | - Kenta Amemiya
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
| | - Tappei Kawakami
- Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Katsuaki Sugawara
- Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan
| | - Kosuke Nakayama
- Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Kohei Yoshimatsu
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai 980-8577, Japan
| | - Hiroshi Kumigashira
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
| | - Takafumi Sato
- Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan
| | - Koji Horiba
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
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21
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Gauthier N, Sobota JA, Pfau H, Gauthier A, Soifer H, Bachmann MD, Fisher IR, Shen ZX, Kirchmann PS. Expanding the momentum field of view in angle-resolved photoemission systems with hemispherical analyzers. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:123907. [PMID: 34972440 DOI: 10.1063/5.0053479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 11/20/2021] [Indexed: 06/14/2023]
Abstract
In photoelectron spectroscopy, the measured electron momentum range is intrinsically related to the excitation photon energy. Low photon energies <10 eV are commonly encountered in laser-based photoemission and lead to a momentum range that is smaller than the Brillouin zones of most materials. This can become a limiting factor when studying condensed matter with laser-based photoemission. An additional restriction is introduced by widely used hemispherical analyzers that record only electrons photoemitted in a solid angle set by the aperture size at the analyzer entrance. Here, we present an upgrade to increase the effective solid angle that is measured with a hemispherical analyzer. We achieve this by accelerating the photoelectrons toward the analyzer with an electric field that is generated by a bias voltage on the sample. Our experimental geometry is comparable to a parallel plate capacitor, and therefore, we approximate the electric field to be uniform along the photoelectron trajectory. With this assumption, we developed an analytic, parameter-free model that relates the measured angles to the electron momenta in the solid and verify its validity by comparing with experimental results on the charge density wave material TbTe3. By providing a larger field of view in momentum space, our approach using a bias potential considerably expands the flexibility of laser-based photoemission setups.
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Affiliation(s)
- Nicolas Gauthier
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Jonathan A Sobota
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Heike Pfau
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Alexandre Gauthier
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Hadas Soifer
- School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Maja D Bachmann
- Geballe Laboratory for Advanced Materials, Departments of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Ian R Fisher
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Zhi-Xun Shen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Patrick S Kirchmann
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
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22
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Schönhense G, Medjanik K, Fedchenko O, Zymaková A, Chernov S, Kutnyakhov D, Vasilyev D, Babenkov S, Elmers HJ, Baumgärtel P, Goslawski P, Öhrwall G, Grunske T, Kauerhof T, von Volkmann K, Kallmayer M, Ellguth M, Oelsner A. Time-of-flight photoelectron momentum microscopy with 80-500 MHz photon sources: electron-optical pulse picker or bandpass pre-filter. JOURNAL OF SYNCHROTRON RADIATION 2021; 28:1891-1908. [PMID: 34738944 PMCID: PMC8570213 DOI: 10.1107/s1600577521010511] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 10/10/2021] [Indexed: 06/13/2023]
Abstract
The small time gaps of synchrotron radiation in conventional multi-bunch mode (100-500 MHz) or laser-based sources with high pulse rate (∼80 MHz) are prohibitive for time-of-flight (ToF) based photoelectron spectroscopy. Detectors with time resolution in the 100 ps range yield only 20-100 resolved time slices within the small time gap. Here we present two techniques of implementing efficient ToF recording at sources with high repetition rate. A fast electron-optical beam blanking unit with GHz bandwidth, integrated in a photoelectron momentum microscope, allows electron-optical `pulse-picking' with any desired repetition period. Aberration-free momentum distributions have been recorded at reduced pulse periods of 5 MHz (at MAX II) and 1.25 MHz (at BESSY II). The approach is compared with two alternative solutions: a bandpass pre-filter (here a hemispherical analyzer) or a parasitic four-bunch island-orbit pulse train, coexisting with the multi-bunch pattern on the main orbit. Chopping in the time domain or bandpass pre-selection in the energy domain can both enable efficient ToF spectroscopy and photoelectron momentum microscopy at 100-500 MHz synchrotrons, highly repetitive lasers or cavity-enhanced high-harmonic sources. The high photon flux of a UV-laser (80 MHz, <1 meV bandwidth) facilitates momentum microscopy with an energy resolution of 4.2 meV and an analyzed region-of-interest (ROI) down to <800 nm. In this novel approach to `sub-µm-ARPES' the ROI is defined by a small field aperture in an intermediate Gaussian image, regardless of the size of the photon spot.
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Affiliation(s)
- G. Schönhense
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - K. Medjanik
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - O. Fedchenko
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - A. Zymaková
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - S. Chernov
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - D. Kutnyakhov
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - D. Vasilyev
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - S. Babenkov
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | - H. J. Elmers
- Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz, Germany
| | | | - P. Goslawski
- BESSY II, Helmholtz-Zentrum, 12489 Berlin, Germany
| | - G. Öhrwall
- MAX IV Laboratory, Lund University, PO Box 118, SE-221 00 Lund, Sweden
| | | | | | | | | | - M. Ellguth
- Surface Concept GmbH, 55128 Mainz, Germany
| | - A. Oelsner
- Surface Concept GmbH, 55128 Mainz, Germany
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23
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Lin C, Ochi M, Noguchi R, Kuroda K, Sakoda M, Nomura A, Tsubota M, Zhang P, Bareille C, Kurokawa K, Arai Y, Kawaguchi K, Tanaka H, Yaji K, Harasawa A, Hashimoto M, Lu D, Shin S, Arita R, Tanda S, Kondo T. Visualization of the strain-induced topological phase transition in a quasi-one-dimensional superconductor TaSe 3. NATURE MATERIALS 2021; 20:1093-1099. [PMID: 34017119 DOI: 10.1038/s41563-021-01004-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 04/01/2021] [Indexed: 06/12/2023]
Abstract
Control of the phase transition from topological to normal insulators can allow for an on/off switching of spin current. While topological phase transitions have been realized by elemental substitution in semiconducting alloys, such an approach requires preparation of materials with various compositions. Thus it is quite far from a feasible device application, which demands a reversible operation. Here we use angle-resolved photoemission spectroscopy and spin- and angle-resolved photoemission spectroscopy to visualize the strain-driven band-structure evolution of the quasi-one-dimensional superconductor TaSe3. We demonstrate that it undergoes reversible strain-induced topological phase transitions from a strong topological insulator phase with spin-polarized, quasi-one-dimensional topological surface states, to topologically trivial semimetal and band insulating phases. The quasi-one-dimensional superconductor TaSe3 provides a suitable platform for engineering the topological spintronics, for example as an on/off switch for a spin current that is robust against impurity scattering.
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Affiliation(s)
- Chun Lin
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - Masayuki Ochi
- Department of Physics, Osaka University, Toyonaka, Japan
| | - Ryo Noguchi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - Kenta Kuroda
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - Masahito Sakoda
- Department of Applied Physics, Hokkaido University, Kita-ku, Japan
| | - Atsushi Nomura
- Department of Physics, Tokyo University of Science, Tokyo, Japan
| | | | - Peng Zhang
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - Cedric Bareille
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - Kifu Kurokawa
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - Yosuke Arai
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - Kaishu Kawaguchi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - Hiroaki Tanaka
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - Koichiro Yaji
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
- Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, Ibaraki, Japan
| | - Ayumi Harasawa
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - Makoto Hashimoto
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Donghui Lu
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Shik Shin
- Office of University Professor, University of Tokyo, Kashiwa, Japan
| | - Ryotaro Arita
- RIKEN Center for Emergent Matter Science, Wako, Japan
- Department of Applied Physics, University of Tokyo, Tokyo, Japan
| | - Satoshi Tanda
- Department of Applied Physics, Hokkaido University, Kita-ku, Japan
- Center of Education and Research for Topological Science and Technology, Hokkaido University, Kita-ku, Japan
| | - Takeshi Kondo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan.
- Trans-scale Quantum Science Institute, University of Tokyo, Tokyo, Japan.
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24
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Lloyd-Hughes J, Oppeneer PM, Pereira Dos Santos T, Schleife A, Meng S, Sentef MA, Ruggenthaler M, Rubio A, Radu I, Murnane M, Shi X, Kapteyn H, Stadtmüller B, Dani KM, da Jornada FH, Prinz E, Aeschlimann M, Milot RL, Burdanova M, Boland J, Cocker T, Hegmann F. The 2021 ultrafast spectroscopic probes of condensed matter roadmap. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:353001. [PMID: 33951618 DOI: 10.1088/1361-648x/abfe21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 05/05/2021] [Indexed: 06/12/2023]
Abstract
In the 60 years since the invention of the laser, the scientific community has developed numerous fields of research based on these bright, coherent light sources, including the areas of imaging, spectroscopy, materials processing and communications. Ultrafast spectroscopy and imaging techniques are at the forefront of research into the light-matter interaction at the shortest times accessible to experiments, ranging from a few attoseconds to nanoseconds. Light pulses provide a crucial probe of the dynamical motion of charges, spins, and atoms on picosecond, femtosecond, and down to attosecond timescales, none of which are accessible even with the fastest electronic devices. Furthermore, strong light pulses can drive materials into unusual phases, with exotic properties. In this roadmap we describe the current state-of-the-art in experimental and theoretical studies of condensed matter using ultrafast probes. In each contribution, the authors also use their extensive knowledge to highlight challenges and predict future trends.
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Affiliation(s)
- J Lloyd-Hughes
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom
| | - P M Oppeneer
- Department of Physics and Astronomy, Uppsala University, PO Box 516, S-75120 Uppsala, Sweden
| | - T Pereira Dos Santos
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
| | - A Schleife
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
- National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
| | - S Meng
- Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - M A Sentef
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science (CFEL), 22761 Hamburg, Germany
| | - M Ruggenthaler
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science (CFEL), 22761 Hamburg, Germany
| | - A Rubio
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science (CFEL), 22761 Hamburg, Germany
- Nano-Bio Spectroscopy Group and ETSF, Universidad del País Vasco UPV/EHU 20018 San Sebastián, Spain
- Center for Computational Quantum Physics (CCQ), The Flatiron Institute, 162 Fifth Avenue, New York, NY, 10010, United States of America
| | - I Radu
- Department of Physics, Freie Universität Berlin, Germany
- Max Born Institute, Berlin, Germany
| | - M Murnane
- JILA, University of Colorado and NIST, Boulder, CO, United States of America
| | - X Shi
- JILA, University of Colorado and NIST, Boulder, CO, United States of America
| | - H Kapteyn
- JILA, University of Colorado and NIST, Boulder, CO, United States of America
| | - B Stadtmüller
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - K M Dani
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
| | - F H da Jornada
- Department of Materials Science and Engineering, Stanford University, Stanford, 94305, CA, United States of America
| | - E Prinz
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - M Aeschlimann
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - R L Milot
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom
| | - M Burdanova
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom
| | - J Boland
- Photon Science Institute, Department of Electrical and Electronic Engineering, University of Manchester, United Kingdom
| | - T Cocker
- Michigan State University, United States of America
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25
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Matsui F, Matsuda H. Projection-type electron spectroscopy collimator analyzer for charged particles and x-ray detections. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:073301. [PMID: 34340415 DOI: 10.1063/5.0051114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 06/08/2021] [Indexed: 06/13/2023]
Abstract
We developed a compact sized device for angular and energy analysis of charged particles in a wide acceptance cone angle of nearly 1π steradian. This device is configured from an electrostatic lens comprising an axisymmetric aspherical mesh, which has a concave shape viewed from the point source, a set of axisymmetric electrodes, planar grids, microchannel plates, and a fluorescent screen positioned coaxially. The potentials of electrodes are adjusted so that the trajectories of the electrons with arbitrarily set kinetic energy are substantially parallelized by the electrostatic lens and enter the planar grid perpendicularly. Instead of the planar grid, a collimator plate with parallel holes can be used as an energy band-pass filter. The angular distribution of electrons with the selected kinetic energy is projected directly onto the fluorescent screen without converging and passing through a pinhole. This is a simple but significant electron-optical design to obtain wide-range angular distribution with high angular resolution, and the analyzer can be suitably used for the two-dimensional angular distribution measurements of electrons and ions emitted from surfaces.
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Affiliation(s)
- Fumihiko Matsui
- UVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan
| | - Hiroyuki Matsuda
- UVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan
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26
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Ueda S, Sakuraba Y. Direct observation of spin-resolved valence band electronic states from a buried magnetic layer with hard X-ray photoemission. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2021; 22:317-325. [PMID: 34025214 PMCID: PMC8128178 DOI: 10.1080/14686996.2021.1912576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/30/2021] [Accepted: 03/30/2021] [Indexed: 06/12/2023]
Abstract
We report spin-resolved hard X-ray photoelectron spectroscopy (spin-HAXPES) for a buried Fe thin film in the valence band region. For the spin-HAXPES experiments, we developed an ultracompact built-in Mott-type spin-filter in a sample carrier, which enabled us to use the merit of two-dimensional (2D) multi-channel detector in a recent photoelectron analyser without modifying an apparatus for HAXPES. The effective Sherman function and the single-channel figure of merit (FOM) of the spin-filter were assessed to be -0.07 and 2.0 × 10-4, respectively. By utilizing the 2D detector of the photoelectron analyser, the effective FOM increased by a factor of ~4 × 104 compared to the case when only 1 channel of the 2D detector was used. We have applied spin-HAXPES to MgO(2 nm)/Fe(50 nm)/MgO(001) structures. The spin-HAXPES experiments revealed the majority and minority spin electronic states and the spin polarisation of the buried Fe thin film. Due to the large photoionization cross-section of the 4s orbital of Fe in HAXPES, the spin-resolved spectra mainly reflected the Fe 3d and 4s states. The observed spin-HAXPES and spin polarisation spectral shapes agreed well with the calculated spin-resolved cross-section weighted densities of states and spin polarisation spectra. In contrast, a small discrepancy in the energy scale was recognised due to the electron correlation effects. These results suggest that the electron correlation effects are important in the electronic structure of bulk Fe, and spin-HAXPES is useful for detecting genuine spin-resolved valence band electronic structures of buried magnetic materials.
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Affiliation(s)
- Shigenori Ueda
- Research Center for Functional Materials, National Institute for Materials Science (NIMS), Tsukuba, Japan
- Research Center for Advanced Measurement and Characterization, NIMS, Tsukuba, Japan
- Synchrotron X-ray Station at SPring-8, NIMS, Hyogo, Japan
| | - Yuya Sakuraba
- Research Center for Magnetic and Spintronic Materials, NIMS, Tsukuba, Japan
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27
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Contrast Inversion of Photoelectron Spectro-microscopy Image. E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 2021. [DOI: 10.1380/ejssnt.2021.42] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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28
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Bedoya-Pinto A, Liu D, Tan H, Pandeya AK, Chang K, Zhang J, Parkin SSP. Large Fermi-Energy Shift and Suppression of Trivial Surface States in NbP Weyl Semimetal Thin Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2008634. [PMID: 33942944 DOI: 10.1002/adma.202008634] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/21/2021] [Indexed: 06/12/2023]
Abstract
Weyl semimetals, a class of 3D topological materials, exhibit a unique electronic structure featuring linear band crossings and disjoint surface states (Fermi-arcs). While first demonstrations of topologically driven phenomena have been realized in bulk crystals, efficient routes to control the electronic structure have remained largely unexplored. Here, a dramatic modification of the electronic structure in epitaxially grown NbP Weyl semimetal thin films is reported, using in situ surface engineering and chemical doping strategies that do not alter the NbP lattice structure and symmetry, retaining its topological nature. Through the preparation of a dangling-bond-free, P-terminated surface which manifests in a surface reconstruction, all the well-known trivial surface states of NbP are fully suppressed, resulting in a purely topological Fermi-arc dispersion. In addition, a substantial Fermi-energy shift from -0.2 to 0.3 eV across the Weyl points is achieved by surface chemical doping, unlocking access to the hitherto unexplored n-type region of the Weyl spectrum. These findings constitute a milestone toward surface-state and Fermi-level engineering of topological bands in Weyl semimetals, and, while there are still challenges in minimizing doping-driven disorder and grain boundary density in the films, they do represent a major advance to realize device heterostructures based on Weyl physics.
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Affiliation(s)
- Amilcar Bedoya-Pinto
- Max Planck-Institute of Microstructure Physics, Weinberg 2, Halle (Saale), 06120, Germany
| | - Defa Liu
- Max Planck-Institute of Microstructure Physics, Weinberg 2, Halle (Saale), 06120, Germany
| | - Hengxin Tan
- Max Planck-Institute of Microstructure Physics, Weinberg 2, Halle (Saale), 06120, Germany
| | | | - Kai Chang
- Max Planck-Institute of Microstructure Physics, Weinberg 2, Halle (Saale), 06120, Germany
| | - Jibo Zhang
- Max Planck-Institute of Microstructure Physics, Weinberg 2, Halle (Saale), 06120, Germany
| | - Stuart S P Parkin
- Max Planck-Institute of Microstructure Physics, Weinberg 2, Halle (Saale), 06120, Germany
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29
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Schönhense G, Kutnyakhov D, Pressacco F, Heber M, Wind N, Agustsson SY, Babenkov S, Vasilyev D, Fedchenko O, Chernov S, Rettig L, Schönhense B, Wenthaus L, Brenner G, Dziarzhytski S, Palutke S, Mahatha SK, Schirmel N, Redlin H, Manschwetus B, Hartl I, Matveyev Y, Gloskovskii A, Schlueter C, Shokeen V, Duerr H, Allison TK, Beye M, Rossnagel K, Elmers HJ, Medjanik K. Suppression of the vacuum space-charge effect in fs-photoemission by a retarding electrostatic front lens. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:053703. [PMID: 34243258 DOI: 10.1063/5.0046567] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 04/04/2021] [Indexed: 06/13/2023]
Abstract
The performance of time-resolved photoemission experiments at fs-pulsed photon sources is ultimately limited by the e-e Coulomb interaction, downgrading energy and momentum resolution. Here, we present an approach to effectively suppress space-charge artifacts in momentum microscopes and photoemission microscopes. A retarding electrostatic field generated by a special objective lens repels slow electrons, retaining the k-image of the fast photoelectrons. The suppression of space-charge effects scales with the ratio of the photoelectron velocities of fast and slow electrons. Fields in the range from -20 to -1100 V/mm for Ekin = 100 eV to 4 keV direct secondaries and pump-induced slow electrons back to the sample surface. Ray tracing simulations reveal that this happens within the first 40 to 3 μm above the sample surface for Ekin = 100 eV to 4 keV. An optimized front-lens design allows switching between the conventional accelerating and the new retarding mode. Time-resolved experiments at Ekin = 107 eV using fs extreme ultraviolet probe pulses from the free-electron laser FLASH reveal that the width of the Fermi edge increases by just 30 meV at an incident pump fluence of 22 mJ/cm2 (retarding field -21 V/mm). For an accelerating field of +2 kV/mm and a pump fluence of only 5 mJ/cm2, it increases by 0.5 eV (pump wavelength 1030 nm). At the given conditions, the suppression mode permits increasing the slow-electron yield by three to four orders of magnitude. The feasibility of the method at high energies is demonstrated without a pump beam at Ekin = 3830 eV using hard x rays from the storage ring PETRA III. The approach opens up a previously inaccessible regime of pump fluences for photoemission experiments.
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Affiliation(s)
- G Schönhense
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
| | - D Kutnyakhov
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - F Pressacco
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - M Heber
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - N Wind
- University of Hamburg, Institut für Experimentalphysik, D-22761 Hamburg, Germany
| | - S Y Agustsson
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
| | - S Babenkov
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
| | - D Vasilyev
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
| | - O Fedchenko
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
| | - S Chernov
- Departments of Chemistry and Physics, Stony Brook University, Stony Brook, New York 11790-3400, USA
| | - L Rettig
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, D-14195 Berlin, Germany
| | - B Schönhense
- Department of Bioengineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - L Wenthaus
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - G Brenner
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - S Dziarzhytski
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - S Palutke
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - S K Mahatha
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - N Schirmel
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - H Redlin
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - B Manschwetus
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - I Hartl
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - Yu Matveyev
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - A Gloskovskii
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - C Schlueter
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - V Shokeen
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala, Sweden
| | - H Duerr
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala, Sweden
| | - T K Allison
- Departments of Chemistry and Physics, Stony Brook University, Stony Brook, New York 11790-3400, USA
| | - M Beye
- Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - K Rossnagel
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany
| | - H J Elmers
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
| | - K Medjanik
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
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30
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Han Y, Zhang H, Yu Y, Liu Z. In Situ Characterization of Catalysis and Electrocatalysis Using APXPS. ACS Catal 2021. [DOI: 10.1021/acscatal.0c04251] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yong Han
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- Center for Transformative Science, ShanghaiTech University, Shanghai 201210, China
| | - Hui Zhang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Yi Yu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- Center for Transformative Science, ShanghaiTech University, Shanghai 201210, China
| | - Zhi Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- Center for Transformative Science, ShanghaiTech University, Shanghai 201210, China
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31
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Xian RP, Acremann Y, Agustsson SY, Dendzik M, Bühlmann K, Curcio D, Kutnyakhov D, Pressacco F, Heber M, Dong S, Pincelli T, Demsar J, Wurth W, Hofmann P, Wolf M, Scheidgen M, Rettig L, Ernstorfer R. An open-source, end-to-end workflow for multidimensional photoemission spectroscopy. Sci Data 2020; 7:442. [PMID: 33335108 PMCID: PMC7746702 DOI: 10.1038/s41597-020-00769-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 11/13/2020] [Indexed: 12/18/2022] Open
Abstract
Characterization of the electronic band structure of solid state materials is routinely performed using photoemission spectroscopy. Recent advancements in short-wavelength light sources and electron detectors give rise to multidimensional photoemission spectroscopy, allowing parallel measurements of the electron spectral function simultaneously in energy, two momentum components and additional physical parameters with single-event detection capability. Efficient processing of the photoelectron event streams at a rate of up to tens of megabytes per second will enable rapid band mapping for materials characterization. We describe an open-source workflow that allows user interaction with billion-count single-electron events in photoemission band mapping experiments, compatible with beamlines at 3rd and 4rd generation light sources and table-top laser-based setups. The workflow offers an end-to-end recipe from distributed operations on single-event data to structured formats for downstream scientific tasks and storage to materials science database integration. Both the workflow and processed data can be archived for reuse, providing the infrastructure for documenting the provenance and lineage of photoemission data for future high-throughput experiments.
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Affiliation(s)
- R Patrick Xian
- Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany.
| | - Yves Acremann
- Laboratory for Solid State Physics, ETH Zurich, 8093, Zurich, Switzerland
| | | | - Maciej Dendzik
- Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany
| | - Kevin Bühlmann
- Laboratory for Solid State Physics, ETH Zurich, 8093, Zurich, Switzerland
| | - Davide Curcio
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000, Aarhus C, Denmark
| | | | - Federico Pressacco
- DESY Photon Science, 22607, Hamburg, Germany
- Department of Physics, University of Hamburg, 22761, Hamburg, Germany
| | | | - Shuo Dong
- Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany
| | - Tommaso Pincelli
- Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany
| | - Jure Demsar
- Institute of Physics, University of Mainz, 55128, Mainz, Germany
| | - Wilfried Wurth
- DESY Photon Science, 22607, Hamburg, Germany
- Department of Physics, University of Hamburg, 22761, Hamburg, Germany
| | - Philip Hofmann
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000, Aarhus C, Denmark
| | - Martin Wolf
- Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany
| | - Markus Scheidgen
- Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany
- Department of Physics, Humboldt University of Berlin, 12489, Berlin, Germany
| | - Laurenz Rettig
- Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany.
| | - Ralph Ernstorfer
- Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany.
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32
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Schönhense G, Babenkov S, Vasilyev D, Elmers HJ, Medjanik K. Single-hemisphere photoelectron momentum microscope with time-of-flight recording. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:123110. [PMID: 33379996 DOI: 10.1063/5.0024074] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 11/26/2020] [Indexed: 06/12/2023]
Abstract
Photoelectron momentum microscopy is an emerging powerful method for angle-resolved photoelectron spectroscopy (ARPES), especially in combination with imaging spin filters. These instruments record kx-ky images, typically exceeding a full Brillouin zone. As energy filters, double-hemispherical or time-of-flight (ToF) devices are in use. Here, we present a new approach for momentum mapping of the full half-space, based on a large single hemispherical analyzer (path radius of 225 mm). Excitation by an unfocused He lamp yielded an energy resolution of 7.7 meV. The performance is demonstrated by k-imaging of quantum-well states in Au and Xe multilayers. The α2-aberration term (α, entrance angle in the dispersive plane) and the transit-time spread of the electrons in the spherical field are studied in a large pass-energy (6 eV-660 eV) and angular range (α up to ±7°). It is discussed how the method circumvents the preconditions of previous theoretical work on the resolution limitation due to the α2-term and the transit-time spread, being detrimental for time-resolved experiments. Thanks to k-resolved detection, both effects can be corrected numerically. We introduce a dispersive-plus-ToF hybrid mode of operation, with an imaging ToF analyzer behind the exit slit of the hemisphere. This instrument captures 3D data arrays I (EB, kx, ky), yielding a gain up to N2 in recording efficiency (N being the number of resolved time slices). A key application will be ARPES at sources with high pulse rates such as synchrotrons with 500 MHz time structure.
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Affiliation(s)
- G Schönhense
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - S Babenkov
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - D Vasilyev
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - H-J Elmers
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - K Medjanik
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
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33
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Maklar J, Dong S, Beaulieu S, Pincelli T, Dendzik M, Windsor YW, Xian RP, Wolf M, Ernstorfer R, Rettig L. A quantitative comparison of time-of-flight momentum microscopes and hemispherical analyzers for time- and angle-resolved photoemission spectroscopy experiments. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:123112. [PMID: 33379994 DOI: 10.1063/5.0024493] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/26/2020] [Indexed: 06/12/2023]
Abstract
Time-of-flight-based momentum microscopy has a growing presence in photoemission studies, as it enables parallel energy- and momentum-resolved acquisition of the full photoelectron distribution. Here, we report table-top extreme ultraviolet time- and angle-resolved photoemission spectroscopy (trARPES) featuring both a hemispherical analyzer and a momentum microscope within the same setup. We present a systematic comparison of the two detection schemes and quantify experimentally relevant parameters, including pump- and probe-induced space-charge effects, detection efficiency, photoelectron count rates, and depth of focus. We highlight the advantages and limitations of both instruments based on exemplary trARPES measurements of bulk WSe2. Our analysis demonstrates the complementary nature of the two spectrometers for time-resolved ARPES experiments. Their combination in a single experimental apparatus allows us to address a broad range of scientific questions with trARPES.
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Affiliation(s)
- J Maklar
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - S Dong
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - S Beaulieu
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - T Pincelli
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - M Dendzik
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Y W Windsor
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - R P Xian
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - M Wolf
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - R Ernstorfer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - L Rettig
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
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34
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Detection of femtosecond spin injection into a thin gold layer by time and spin resolved photoemission. Sci Rep 2020; 10:12632. [PMID: 32724122 PMCID: PMC7387461 DOI: 10.1038/s41598-020-69477-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 07/13/2020] [Indexed: 11/14/2022] Open
Abstract
The ultrafast demagnetization effect allows for the generation of femtosecond spin current pulses, which is expected to extend the fields of spin transport and spintronics to the femtosecond time domain. Thus far, directly observing the spin polarization induced by spin injection on the femtosecond time scale has not been possible. Herein, we present time- and spin-resolved photoemission results of spin injection from a laser-excited ferromagnet into a thin gold layer. The injected spin polarization is aligned along the magnetization direction of the underlying ferromagnet. Its decay time depends on the thickness of the gold layer, indicating that transport as well as storage of spins are relevant. This capacitive aspect of spin transport may limit the speed of future spintronic devices.
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35
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Keunecke M, Möller C, Schmitt D, Nolte H, Jansen GSM, Reutzel M, Gutberlet M, Halasi G, Steil D, Steil S, Mathias S. Time-resolved momentum microscopy with a 1 MHz high-harmonic extreme ultraviolet beamline. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:063905. [PMID: 32611056 DOI: 10.1063/5.0006531] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 06/04/2020] [Indexed: 06/11/2023]
Abstract
Recent progress in laser-based high-repetition rate extreme ultraviolet (EUV) light sources and multidimensional photoelectron spectroscopy enables the build-up of a new generation of time-resolved photoemission experiments. Here, we present a setup for time-resolved momentum microscopy driven by a 1 MHz fs EUV table-top light source optimized for the generation of 26.5 eV photons. The setup provides simultaneous access to the temporal evolution of the photoelectron's kinetic energy and in-plane momentum. We discuss opportunities and limitations of our new experiment based on a series of static and time-resolved measurements on graphene.
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Affiliation(s)
- Marius Keunecke
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Christina Möller
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - David Schmitt
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Hendrik Nolte
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - G S Matthijs Jansen
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Marcel Reutzel
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Marie Gutberlet
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Gyula Halasi
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Daniel Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Sabine Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Stefan Mathias
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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36
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Bedoya-Pinto A, Pandeya AK, Liu D, Deniz H, Chang K, Tan H, Han H, Jena J, Kostanovskiy I, Parkin SSP. Realization of Epitaxial NbP and TaP Weyl Semimetal Thin Films. ACS NANO 2020; 14:4405-4413. [PMID: 32053338 PMCID: PMC7307967 DOI: 10.1021/acsnano.9b09997] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 02/13/2020] [Indexed: 06/10/2023]
Abstract
Weyl semimetals (WSMs) exhibit an electronic structure governed by linear band dispersions and degenerate (Weyl) points that lead to exotic physical phenomena. While WSMs were established in bulk monopnictide compounds several years ago, the growth of thin films remains a challenge. Here, we report the bottom-up synthesis of single-crystalline NbP and TaP thin films, 9 to 70 nm thick, by means of molecular beam epitaxy. The as-grown epitaxial films feature a phosphorus-rich stoichiometry, a tensile-strained unit cell, and a homogeneous surface termination, unlike their bulk crystal counterparts. These properties result in an electronic structure governed by topological surface states as directly observed using in situ momentum photoemission microscopy, along with a Fermi-level shift of -0.2 eV with respect to the intrinsic chemical potential. Although the Fermi energy of the as-grown samples is still far from the Weyl points, carrier mobilities close to 103 cm2/(V s) have been measured at room temperature in patterned Hall-bar devices. The ability to grow thin films of Weyl semimetals that can be tailored by doping or strain, is an important step toward the fabrication of functional WSM-based devices and heterostructures.
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Affiliation(s)
- Amilcar Bedoya-Pinto
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | | | - Defa Liu
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Hakan Deniz
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Kai Chang
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Hengxin Tan
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Hyeon Han
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Jagannath Jena
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Ilya Kostanovskiy
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Stuart S. P. Parkin
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
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37
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Angrick C, Braun J, Ebert H, Donath M. Spin-dependent electron reflection at W(110). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 33:115001. [PMID: 33316786 DOI: 10.1088/1361-648x/abd338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Spin-dependent reflection of low-energy electrons at the W(110) surface caused by spin-orbit interaction was studied experimentally and theoretically. Comprehensive information for a wide range of electron incidence angles and energies was collected via maps for the reflectivity, the spin-dependent reflection asymmetry, and the figure of merit of the spin separation. The experimental results are compared with calculations of the scattering process using a realistic surface potential barrier. The results are discussed in view of possible applications of W(110) as a scattering target in spin-polarization detectors. Possible working points for use in single- as well as multi-channel spin-polarization-detection devices are identified and discussed.
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Affiliation(s)
- C Angrick
- Physikalisches Institut, Westfälische Wilhelms-Universität, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
| | - J Braun
- Department Chemie, Physikalische Chemie, Ludwig-Maximilians-Universität, Butenandtstraße 11, 81377 München, Germany
| | - H Ebert
- Department Chemie, Physikalische Chemie, Ludwig-Maximilians-Universität, Butenandtstraße 11, 81377 München, Germany
| | - M Donath
- Physikalisches Institut, Westfälische Wilhelms-Universität, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
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38
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From Photoemission Microscopy to an “All-in-One” Photoemission Experiment. E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 2020. [DOI: 10.1380/ejssnt.2020.48] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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39
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Kutnyakhov D, Xian RP, Dendzik M, Heber M, Pressacco F, Agustsson SY, Wenthaus L, Meyer H, Gieschen S, Mercurio G, Benz A, Bühlman K, Däster S, Gort R, Curcio D, Volckaert K, Bianchi M, Sanders C, Miwa JA, Ulstrup S, Oelsner A, Tusche C, Chen YJ, Vasilyev D, Medjanik K, Brenner G, Dziarzhytski S, Redlin H, Manschwetus B, Dong S, Hauer J, Rettig L, Diekmann F, Rossnagel K, Demsar J, Elmers HJ, Hofmann P, Ernstorfer R, Schönhense G, Acremann Y, Wurth W. Time- and momentum-resolved photoemission studies using time-of-flight momentum microscopy at a free-electron laser. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:013109. [PMID: 32012554 DOI: 10.1063/1.5118777] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 11/30/2019] [Indexed: 06/10/2023]
Abstract
Time-resolved photoemission with ultrafast pump and probe pulses is an emerging technique with wide application potential. Real-time recording of nonequilibrium electronic processes, transient states in chemical reactions, or the interplay of electronic and structural dynamics offers fascinating opportunities for future research. Combining valence-band and core-level spectroscopy with photoelectron diffraction for electronic, chemical, and structural analyses requires few 10 fs soft X-ray pulses with some 10 meV spectral resolution, which are currently available at high repetition rate free-electron lasers. We have constructed and optimized a versatile setup commissioned at FLASH/PG2 that combines free-electron laser capabilities together with a multidimensional recording scheme for photoemission studies. We use a full-field imaging momentum microscope with time-of-flight energy recording as the detector for mapping of 3D band structures in (kx, ky, E) parameter space with unprecedented efficiency. Our instrument can image full surface Brillouin zones with up to 7 Å-1 diameter in a binding-energy range of several eV, resolving about 2.5 × 105 data voxels simultaneously. Using the ultrafast excited state dynamics in the van der Waals semiconductor WSe2 measured at photon energies of 36.5 eV and 109.5 eV, we demonstrate an experimental energy resolution of 130 meV, a momentum resolution of 0.06 Å-1, and a system response function of 150 fs.
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Affiliation(s)
- D Kutnyakhov
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - R P Xian
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - M Dendzik
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - M Heber
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - F Pressacco
- Physics Department and Centre for Free-Electron Laser Science (CFEL), University of Hamburg, 22761 Hamburg, Germany
| | - S Y Agustsson
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - L Wenthaus
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - H Meyer
- Physics Department and Centre for Free-Electron Laser Science (CFEL), University of Hamburg, 22761 Hamburg, Germany
| | - S Gieschen
- Physics Department and Centre for Free-Electron Laser Science (CFEL), University of Hamburg, 22761 Hamburg, Germany
| | - G Mercurio
- Physics Department and Centre for Free-Electron Laser Science (CFEL), University of Hamburg, 22761 Hamburg, Germany
| | - A Benz
- Physics Department and Centre for Free-Electron Laser Science (CFEL), University of Hamburg, 22761 Hamburg, Germany
| | - K Bühlman
- Laboratorium für Festkörperphysik, ETH Zürich, 8093 Zürich, Switzerland
| | - S Däster
- Laboratorium für Festkörperphysik, ETH Zürich, 8093 Zürich, Switzerland
| | - R Gort
- Laboratorium für Festkörperphysik, ETH Zürich, 8093 Zürich, Switzerland
| | - D Curcio
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - K Volckaert
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - M Bianchi
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - Ch Sanders
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell OX11 0QX, United Kingdom
| | - J A Miwa
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - S Ulstrup
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - A Oelsner
- Surface Concept GmbH, 55124 Mainz, Germany
| | - C Tusche
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52428 Jülich, Germany
| | - Y-J Chen
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52428 Jülich, Germany
| | - D Vasilyev
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - K Medjanik
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - G Brenner
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - S Dziarzhytski
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - H Redlin
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - B Manschwetus
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - S Dong
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - J Hauer
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - L Rettig
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - F Diekmann
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - K Rossnagel
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - J Demsar
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - H-J Elmers
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - Ph Hofmann
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - R Ernstorfer
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - G Schönhense
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - Y Acremann
- Laboratorium für Festkörperphysik, ETH Zürich, 8093 Zürich, Switzerland
| | - W Wurth
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
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40
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Medjanik K, Babenkov SV, Chernov S, Vasilyev D, Schönhense B, Schlueter C, Gloskovskii A, Matveyev Y, Drube W, Elmers HJ, Schönhense G. Progress in HAXPES performance combining full-field k-imaging with time-of-flight recording. JOURNAL OF SYNCHROTRON RADIATION 2019; 26:1996-2012. [PMID: 31721745 PMCID: PMC6853377 DOI: 10.1107/s1600577519012773] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 09/13/2019] [Indexed: 05/27/2023]
Abstract
An alternative approach to hard-X-ray photoelectron spectroscopy (HAXPES) has been established. The instrumental key feature is an increase of the dimensionality of the recording scheme from 2D to 3D. A high-energy momentum microscope detects electrons with initial kinetic energies up to 8 keV with a k-resolution of 0.025 Å-1, equivalent to an angular resolution of 0.034°. A special objective lens with k-space acceptance up to 25 Å-1 allows for simultaneous full-field imaging of many Brillouin zones. Combined with time-of-flight (ToF) parallel energy recording this yields maximum parallelization. Thanks to the high brilliance (1013 hν s-1 in a spot of <20 µm diameter) of beamline P22 at PETRA III (Hamburg, Germany), the microscope set a benchmark in HAXPES recording speed, i.e. several million counts per second for core-level signals and one million for d-bands of transition metals. The concept of tomographic k-space mapping established using soft X-rays works equally well in the hard X-ray range. Sharp valence band k-patterns of Re, collected at an excitation energy of 6 keV, correspond to direct transitions to the 28th repeated Brillouin zone. Measured total energy resolutions (photon bandwidth plus ToF-resolution) are 62 meV and 180 meV FWHM at 5.977 keV for monochromator crystals Si(333) and Si(311) and 450 meV at 4.0 keV for Si(111). Hard X-ray photoelectron diffraction (hXPD) patterns with rich fine structure are recorded within minutes. The short photoelectron wavelength (10% of the interatomic distance) `amplifies' phase differences, making full-field hXPD a sensitive structural tool.
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Affiliation(s)
- K. Medjanik
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - S. V. Babenkov
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - S. Chernov
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - D. Vasilyev
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - B. Schönhense
- Department of Bioengineering, Imperial College London, UK
| | - C. Schlueter
- DESY Photon Science, Notkestrasse 85, 22607 Hamburg, Germany
| | - A. Gloskovskii
- DESY Photon Science, Notkestrasse 85, 22607 Hamburg, Germany
| | - Yu. Matveyev
- DESY Photon Science, Notkestrasse 85, 22607 Hamburg, Germany
| | - W. Drube
- DESY Photon Science, Notkestrasse 85, 22607 Hamburg, Germany
| | - H. J. Elmers
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - G. Schönhense
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
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41
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Mankos M, Shadman K, Hahn R, Picard YJ, Comparat D, Fedchenko O, Schönhense G, Amiaud L, Lafosse A, Barrett N. Design for a high resolution electron energy loss microscope. Ultramicroscopy 2019; 207:112848. [PMID: 31606484 DOI: 10.1016/j.ultramic.2019.112848] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 09/14/2019] [Accepted: 09/24/2019] [Indexed: 11/27/2022]
Abstract
An electron optical column has been designed for High Resolution Electron Energy Loss Microscopy (HREELM). The column is composed of electron lenses and a beam separator that are placed between an electron source based on a laser excited cesium atom beam and a time-of-flight (ToF) spectrometer or a hemispherical analyzer (HSA). The instrument will be able to perform full field low energy electron imaging of surfaces with sub-micron spatial resolution and meV energy resolution necessary for the analysis of local vibrational spectra. Thus, non-contact, real space mapping of microscopic variations in vibrational levels will be made possible. A second imaging mode will allow for the mapping of the phonon dispersion relations from microscopic regions defined by an appropriate field aperture.
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Affiliation(s)
- Marian Mankos
- Electron Optica Inc., 1000 Elwell Court Ste.110, Palo Alto, CA 94303, USA
| | - Khashayar Shadman
- Electron Optica Inc., 1000 Elwell Court Ste.110, Palo Alto, CA 94303, USA
| | - Raphaël Hahn
- Laboratoire Aimé Cotton, CNRS, Univ. Paris-Sud, ENS Paris Saclay, Université Paris-Saclay, Bât. 505, Orsay 91405, France
| | - Yan J Picard
- Laboratoire Aimé Cotton, CNRS, Univ. Paris-Sud, ENS Paris Saclay, Université Paris-Saclay, Bât. 505, Orsay 91405, France
| | - Daniel Comparat
- Laboratoire Aimé Cotton, CNRS, Univ. Paris-Sud, ENS Paris Saclay, Université Paris-Saclay, Bât. 505, Orsay 91405, France
| | - Olena Fedchenko
- Johannes Gutenberg Universität Mainz, Inst. für Physik, Mainz 55128, Germany
| | - Gerd Schönhense
- Johannes Gutenberg Universität Mainz, Inst. für Physik, Mainz 55128, Germany
| | - Lionel Amiaud
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ Paris-Sud, Université Paris-Saclay, Orsay F-91405, France
| | - Anne Lafosse
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ Paris-Sud, Université Paris-Saclay, Orsay F-91405, France
| | - Nick Barrett
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, Gif-sur-Yvette Cedex 91191, France.
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42
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Yamane H, Matsui F, Ueba T, Horigome T, Makita S, Tanaka K, Kera S, Kosugi N. Acceptance-cone-tunable electron spectrometer for highly-efficient constant energy mapping. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:093102. [PMID: 31575223 DOI: 10.1063/1.5109453] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 08/12/2019] [Indexed: 06/10/2023]
Abstract
We have developed an acceptance-cone-tunable (ACT) electron spectrometer for the highly efficient constant-energy photoelectron mapping of functional materials. The ACT spectrometer consists of the hemispherical deflection analyzer with the mesh-type electrostatic lens near the sample. The photoelectron trajectory can be converged by applying a negative bias to the sample and grounding the mesh lens and the analyzer entrance. The performance of the present ACT spectrometer with neither rotating nor tilting of the sample is demonstrated by the wide-angle observation of the well-known π-band dispersion of a single crystalline graphite over the Brillouin zone. The acceptance cone of the spectrometer is expanded by a factor of 3.30 when the negative bias voltage is 10 times as high as the kinetic energy of photoelectrons.
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Affiliation(s)
- Hiroyuki Yamane
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
| | - Fumihiko Matsui
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
| | - Takahiro Ueba
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
| | - Toshio Horigome
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
| | - Seiji Makita
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
| | - Kiyohisa Tanaka
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
| | - Satoshi Kera
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
| | - Nobuhiro Kosugi
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
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43
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Imaging properties of hemispherical electrostatic energy analyzers for high resolution momentum microscopy. Ultramicroscopy 2019; 206:112815. [PMID: 31325896 DOI: 10.1016/j.ultramic.2019.112815] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 07/07/2019] [Indexed: 11/20/2022]
Abstract
Hemispherical deflection analyzers are the most widely used energy filters for state-of-the-art electron spectroscopy. Due to the high spherical symmetry, they are also well suited as imaging energy filters for electron microscopy. Here, we review the imaging properties of hemispherical deflection analyzers with emphasis on the application for cathode lens microscopy. In particular, it turns out that aberrations, in general limiting the image resolution, cancel out at the entrance and exit of the analyzer. This finding allows more compact imaging energy filters for momentum microscopy or photoelectron emission microscopy. For instance, high resolution imaging is possible, using only a single hemisphere. Conversely, a double pass hemispherical analyzer can double the energy dispersion, which means it can double the energy resolution at certain transmission, or can multiply the transmission at certain energy resolution.
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44
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Plucinski L. Band structure engineering in 3D topological insulators. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:183001. [PMID: 30731442 DOI: 10.1088/1361-648x/ab052c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The discovery of novel topological phases has revolutionized the way we think about electronic matter. Topologically protected states have been demonstrated for many materials, however, creating materials that exhibit desired properties often remains a challenge. For example, one of the key challenges in three dimensional topological insulators has been the realization of insulating bulk, such that the unique properties of surface states could be fully employed in electron transport applications. Further challenges are in creating materials that simultaneously exhibit states protected by various symmetries on their different surfaces, inducing magnetic exchange coupling into the topological materials, as well as potentially creating non-trivial transient electronic states. This review presents theoretical concepts and a selection of experimental results from the point view of a spectroscopist, and as such might be useful for physicists who want to get familiar with the key concepts in a self-contained form with formalism reduced to readily understandable concepts.
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Affiliation(s)
- L Plucinski
- Peter Grünberg Institut PGI-6, Forschungszentrum Jülich, D-52425 Jülich, Germany. Jülich Aachen Research Alliance-Fundamentals of Future Information Technologies (JARA-FIT), 52425 Jülich, Germany
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45
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Stadtmüller B, Grad L, Seidel J, Haag F, Haag N, Cinchetti M, Aeschlimann M. Modification of Pb quantum well states by the adsorption of organic molecules. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:134005. [PMID: 30625428 DOI: 10.1088/1361-648x/aafcf5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The successful implementation of nanoscale materials in next generation optoelectronic devices crucially depends on our ability to functionalize and design low dimensional materials according to the desired field of application. Recently, organic adsorbates have revealed an enormous potential to alter the occupied surface band structure of tunable materials by the formation of tailored molecule-surface bonds. Here, we extend this concept of adsorption-induced surface band structure engineering to the unoccupied part of the surface band structure. This is achieved by our comprehensive investigation of the unoccupied band structure of a lead (Pb) monolayer film on the Ag(1 1 1) surface prior and after the adsorption of one monolayer of the aromatic molecule 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA). Using two-photon momentum microscopy, we show that the unoccupied states of the Pb/Ag(1 1 1) bilayer system are dominated by a parabolic quantum well state (QWS) in the center of the surface Brillouin zone with Pb p[Formula: see text] orbital character and a side band with almost linear dispersion showing Pb p[Formula: see text] orbital character. After the adsorption of PTCDA, the Pb side band remains completely unaffected while the signal of the Pb QWS is fully suppressed. This adsorption induced change in the unoccupied Pb band structure coincides with an interfacial charge transfer from the Pb layer into the PTCDA molecule. We propose that this charge transfer and the correspondingly vertical (partially chemical) interaction across the PTCDA/Pb interface suppresses the existence of the QWS in the Pb layer. Our results hence unveil a new possibility to orbital selectively tune and control the entire surface band structure of low dimensional systems by the adsorption of organic molecules.
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Affiliation(s)
- Benjamin Stadtmüller
- Department of Physics and OPTIMAS Research Center, TU Kaiserslautern, Erwin-Schrödinger-Strasse 46, 67663 Kaiserslautern, Germany. Graduate School of Excellence Materials Science in Mainz, Erwin-Schrödinger-Strasse 46, 67663 Kaiserslautern, Germany
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46
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Min CH, Bentmann H, Neu JN, Eck P, Moser S, Figgemeier T, Ünzelmann M, Kissner K, Lutz P, Koch RJ, Jozwiak C, Bostwick A, Rotenberg E, Thomale R, Sangiovanni G, Siegrist T, Di Sante D, Reinert F. Orbital Fingerprint of Topological Fermi Arcs in the Weyl Semimetal TaP. PHYSICAL REVIEW LETTERS 2019; 122:116402. [PMID: 30951331 DOI: 10.1103/physrevlett.122.116402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 11/19/2018] [Indexed: 06/09/2023]
Abstract
The monopnictides TaAs and TaP are well-established Weyl semimetals. Yet, a precise assignment of Fermi arcs, accommodating the predicted chiral charge of the bulk Weyl points, has been difficult in these systems, and the topological character of different surface features in the Fermi surface is not fully understood. Here, employing a joint analysis from linear dichroism in angle-resolved photoemission and first-principles calculations, we unveil the orbital texture on the full Fermi surface of TaP(001). We observe pronounced switches in the orbital texture at the projected Weyl nodes, and show how they facilitate a topological classification of the surface band structure. Our findings establish a critical role of the orbital degrees of freedom in mediating the surface-bulk connectivity in Weyl semimetals.
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Affiliation(s)
- Chul-Hee Min
- Experimentelle Physik VII, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Hendrik Bentmann
- Experimentelle Physik VII, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Jennifer N Neu
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - Philipp Eck
- Theoretische Physik I, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Simon Moser
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Tim Figgemeier
- Experimentelle Physik VII, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Maximilian Ünzelmann
- Experimentelle Physik VII, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Katharina Kissner
- Experimentelle Physik VII, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Peter Lutz
- Experimentelle Physik VII, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Roland J Koch
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Chris Jozwiak
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Aaron Bostwick
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Eli Rotenberg
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Ronny Thomale
- Theoretische Physik I, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Giorgio Sangiovanni
- Theoretische Physik I, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Theo Siegrist
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, Florida 32310, USA
| | - Domenico Di Sante
- Theoretische Physik I, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Friedrich Reinert
- Experimentelle Physik VII, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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47
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Polyakov A, Mohseni K, Castro GR, Rubio-Zuazo J, Zeugner A, Isaeva A, Chen YJ, Tusche C, Meyerheim HL. A bismuth triiodide monosheet on Bi 2Se 3(0001). Sci Rep 2019; 9:4052. [PMID: 30858434 PMCID: PMC6411853 DOI: 10.1038/s41598-019-40506-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 02/18/2019] [Indexed: 12/02/2022] Open
Abstract
A stable BiI3 monosheet has been grown for the first time on the (0001) surface of the topological insulator Bi2Se3 as confirmed by scanning tunnelling microscopy, surface X-ray diffraction, and X-ray photoemision spectroscopy. BiI3 is deposited by molecular beam epitaxy from the crystalline BiTeI precursor that undergoes decomposition sublimation. The key fragment of the bulk BiI3 structure, \documentclass[12pt]{minimal}
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\begin{document}$${{\rm{a}}}_{\infty }^{2}$$\end{document}a∞2[I—Bi—I] layer of edge-sharing BiI6 octahedra, is preserved in the ultra-thin film limit, but exhibits large atomic relaxations. The stacking sequence of the trilayers and alternations of the Bi—I distances in the monosheet are the same as in the bulk BiI3 structure. Momentum resolved photoemission spectroscopy indicates a direct band gap of 1.2 eV. The Dirac surface state is completely destroyed and a new flat band appears in the band gap of the BiI3 film that could be interpreted as an interface state.
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Affiliation(s)
- Andrey Polyakov
- Max-Planck-Institut für Mikrostukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Katayoon Mohseni
- Max-Planck-Institut für Mikrostukturphysik, Weinberg 2, 06120, Halle, Germany
| | - German R Castro
- SpLine, Spanish CRG BM25 Beamline at the ESRF (The European Synchrotron), F-38000, Grenoble, France.,Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (ICMM-CSIC), 28049, Madrid, Spain
| | - Juan Rubio-Zuazo
- SpLine, Spanish CRG BM25 Beamline at the ESRF (The European Synchrotron), F-38000, Grenoble, France.,Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (ICMM-CSIC), 28049, Madrid, Spain
| | - Alexander Zeugner
- Department of Chemistry and Food Chemistry, TU Dresden, Helmholtzstraße 10, 01069, Dresden, Germany
| | - Anna Isaeva
- Technische Universität Dresden, Institut für Festkörper- und Materialphysik, Helmholtzstraße 10, 01069, Dresden, Germany.,Leibniz-Institut für Festkörper-und Werkstoffforschung Dresden, Helmholtzstraße 20, 01069, Dresden, Germany
| | - Ying-Jiun Chen
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany.,Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Christian Tusche
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany.,Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Holger L Meyerheim
- Max-Planck-Institut für Mikrostukturphysik, Weinberg 2, 06120, Halle, Germany.
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48
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Kink far below the Fermi level reveals new electron-magnon scattering channel in Fe. Nat Commun 2019; 10:505. [PMID: 30705281 PMCID: PMC6355843 DOI: 10.1038/s41467-019-08445-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 01/04/2019] [Indexed: 11/25/2022] Open
Abstract
Many properties of real materials can be modeled using ab initio methods within a single-particle picture. However, for an accurate theoretical treatment of excited states, it is necessary to describe electron-electron correlations including interactions with bosons: phonons, plasmons, or magnons. In this work, by comparing spin- and momentum-resolved photoemission spectroscopy measurements to many-body calculations carried out with a newly developed first-principles method, we show that a kink in the electronic band dispersion of a ferromagnetic material can occur at much deeper binding energies than expected (Eb = 1.5 eV). We demonstrate that the observed spectral signature reflects the formation of a many-body state that includes a photohole bound to a coherent superposition of renormalized spin-flip excitations. The existence of such a many-body state sheds new light on the physics of the electron-magnon interaction which is essential in fields such as spintronics and Fe-based superconductivity. The conduction electron and magnon interactions are essential for the understanding and development of spintronics and superconductivity. Here the authors show a deep binding energy kink in spin-resolved photoemission spectra which is understood as a signature the many-body spin flip excitation in Fe single crystal thin film.
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49
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Matsuda H, Tóth L, Daimon H. Variable-deceleration-ratio wide-acceptance-angle electrostatic lens for two-dimensional angular and energy analysis. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:123105. [PMID: 30599611 DOI: 10.1063/1.5043317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 11/08/2018] [Indexed: 06/09/2023]
Abstract
Variable-deceleration-ratio wide-acceptance-angle electrostatic lens (VD-WAAEL) is proposed as a potential technique for two-dimensional angular and energy analysis. The basic features of the lens are studied using the charge simulation method and ray tracing calculation. The lens uses an ellipsoidal mesh electrode and allows a wide acceptance angle of ±50°. Two possible applications of the VD-WAAEL are discussed. One is a simple combination of the VD-WAAEL-projection-lens, in which an aperture is used for energy analysis. The other is a combination of the VD-WAAEL with a conventional electron spectrometer, which is responsible for obtaining higher energy resolution. The former is discussed in detail and the latter is described briefly. While the ray tracing calculation is only for the case of an ideal mesh, a note on the disturbing effect of mesh holes is presented. The best possible energy resolution of the simple VD-WAAEL-projection-lens analyzer seems to be around 1/1000, given a fine mesh electrode to suppress the disturbing effect of mesh holes.
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Affiliation(s)
- Hiroyuki Matsuda
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - László Tóth
- University of Debrecen, Egyetem ter 1, H-4032 Debrecen, Hungary
| | - Hiroshi Daimon
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
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50
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Tusche C, Ellguth M, Feyer V, Krasyuk A, Wiemann C, Henk J, Schneider CM, Kirschner J. Nonlocal electron correlations in an itinerant ferromagnet. Nat Commun 2018; 9:3727. [PMID: 30213929 PMCID: PMC6137183 DOI: 10.1038/s41467-018-05960-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 07/27/2018] [Indexed: 11/29/2022] Open
Abstract
Our understanding of the properties of ferromagnetic materials, widely used in spintronic devices, is fundamentally based on their electronic band structure. However, even for the most simple elemental ferromagnets, electron correlations are prevalent, requiring descriptions of their electronic structure beyond the simple picture of independent quasi-particles. Here, we give evidence that in itinerant ferromagnets like cobalt these electron correlations are of nonlocal origin, manifested in a complex self-energy Σσ(E,k) that disperses as function of spin σ, energy E, and momentum vector k. Together with one-step photoemission calculations, our experiments allow us to quantify the dispersive behaviour of the complex self-energy over the whole Brillouin zone. At the same time we observe regions of anomalously large "waterfall"-like band renormalization, previously only attributed to strong electron correlations in high-TC superconductors, making itinerant ferromagnets a paradigmatic test case for the interplay between band structure, magnetism, and many-body correlations.
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Affiliation(s)
- Christian Tusche
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany.
- Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany.
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany.
| | - Martin Ellguth
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Vitaliy Feyer
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany
| | - Alexander Krasyuk
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Carsten Wiemann
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany
| | - Jürgen Henk
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06120, Halle, Germany
| | - Claus M Schneider
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany
- Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Jürgen Kirschner
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06120, Halle, Germany
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