1
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Tkach O, Vo TP, Fedchenko O, Medjanik K, Lytvynenko Y, Babenkov S, Vasilyev D, Nguyen QL, Peixoto TRF, Gloskowskii A, Schlueter C, Chernov S, Hoesch M, Kutnyakhov D, Scholz M, Wenthaus L, Wind N, Marotzke S, Winkelmann A, Rossnagel K, Minár J, Elmers HJ, Schönhense G. Circular dichroism in hard X-ray photoelectron diffraction observed by time-of-flight momentum microscopy. Ultramicroscopy 2023; 250:113750. [PMID: 37178606 DOI: 10.1016/j.ultramic.2023.113750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 04/01/2023] [Accepted: 05/04/2023] [Indexed: 05/15/2023]
Abstract
X-ray photoelectron diffraction (XPD) is a powerful technique that yields detailed structural information of solids and thin films that complements electronic structure measurements. Among the strongholds of XPD we can identify dopant sites, track structural phase transitions, and perform holographic reconstruction. High-resolution imaging of kll-distributions (momentum microscopy) presents a new approach to core-level photoemission. It yields full-field kx-ky XPD patterns with unprecedented acquisition speed and richness in details. Here, we show that beyond the pure diffraction information, XPD patterns exhibit pronounced circular dichroism in the angular distribution (CDAD) with asymmetries up to 80%, alongside with rapid variations on a small kll-scale (0.1 Å-1). Measurements with circularly-polarized hard X-rays (hν = 6 keV) for a number of core levels, including Si, Ge, Mo and W, prove that core-level CDAD is a general phenomenon that is independent of atomic number. The fine structure in CDAD is more pronounced compared to the corresponding intensity patterns. Additionally, they obey the same symmetry rules as found for atomic and molecular species, and valence bands. The CD is antisymmetric with respect to the mirror planes of the crystal, whose signatures are sharp zero lines. Calculations using both the Bloch-wave approach and one-step photoemission reveal the origin of the fine structure that represents the signature of Kikuchi diffraction. To disentangle the roles of photoexcitation and diffraction, XPD has been implemented into the Munich SPRKKR package to unify the one-step model of photoemission and multiple scattering theory.
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Affiliation(s)
- O Tkach
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany; Sumy State University, Rymskogo-Korsakova 2, 40007 Sumy, Ukraine.
| | - T-P Vo
- New Technologies - Research Centre, Univ. of West Bohemia, 30100 Pilsen, Czech Republic
| | - O Fedchenko
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - K Medjanik
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - Y Lytvynenko
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany; Institute of Magnetism of the NAS of Ukraine and MES of Ukraine, 03142 Kyiv, Ukraine
| | - S Babenkov
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - D Vasilyev
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - Q L Nguyen
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - T R F Peixoto
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - A Gloskowskii
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - C Schlueter
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - S Chernov
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - M Hoesch
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - D Kutnyakhov
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - M Scholz
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - L Wenthaus
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - N Wind
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany; Institut für Experimentalphysik, Universität Hamburg, 22761 Hamburg, Germany
| | - S Marotzke
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany; Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - A Winkelmann
- Academic Centre for Materials and Nanotechn., Univ. of Science and Technology, Kraków, Poland
| | - K Rossnagel
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany; Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - J Minár
- New Technologies - Research Centre, Univ. of West Bohemia, 30100 Pilsen, Czech Republic
| | - H-J Elmers
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - G Schönhense
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
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2
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Fedchenko O, Šmejkal L, Kallmayer M, Lytvynenko Y, Medjanik K, Babenkov S, Vasilyev D, Kläui M, Demsar J, Schönhense G, Jourdan M, Sinova J, Elmers HJ. Direct observation of antiferromagnetic parity violation in the electronic structure of Mn 2Au. J Phys Condens Matter 2022; 34:425501. [PMID: 35940170 DOI: 10.1088/1361-648x/ac87e6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 08/08/2022] [Indexed: 06/15/2023]
Abstract
Using momentum microscopy with sub-µm spatial resolution, allowing momentum resolved photoemission on individual antiferromagnetic domains, we observe an asymmetry in the electronic band structure,E(k)≠E(-k), in Mn2Au. This broken band structure parity originates from the combined time and parity symmetry,PT, of the antiferromagnetic order of the Mn moments, in connection with spin-orbit coupling. The spin-orbit interaction couples the broken parity to the Néel order parameter direction. We demonstrate a novel tool to image the Néel vector direction,N, by combining spatially resolved momentum microscopy withab-initiocalculations that correlate the broken parity with the vectorN.
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Affiliation(s)
- O Fedchenko
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
| | - L Šmejkal
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
- Institute of Physics Academy of Sciences of the Czech Republic, Cukrovarnická 10, Praha 6, Czech Republic
| | - M Kallmayer
- Surface Concept GmbH, Am Sägewerk 23A, D-55124 Mainz, Germany
| | - Ya Lytvynenko
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
- Institute of Magnetism of the National Academy of Science and MES of Ukraine, Vernadsky Blvd, 36b, 03142 Kyiv, Ukraine
| | - K Medjanik
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
| | - S Babenkov
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
| | - D Vasilyev
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
| | - M Kläui
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
| | - J Demsar
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
| | - G Schönhense
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
| | - M Jourdan
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
| | - J Sinova
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
- Institute of Physics Academy of Sciences of the Czech Republic, Cukrovarnická 10, Praha 6, Czech Republic
| | - H J Elmers
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany
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3
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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. J Synchrotron Radiat 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] [What about the content of this article? (0)] [Affiliation(s)] [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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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. Rev Sci Instrum 2021; 92:053703. [PMID: 34243258 DOI: 10.1063/5.0046567] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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5
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Agustsson SY, Chernov SV, Medjanik K, Babenkov S, Fedchenko O, Vasilyev D, Schlueter C, Gloskovskii A, Matveyev Y, Kliemt K, Krellner C, Demsar J, Schönhense G, Elmers HJ. Temperature-dependent change of the electronic structure in the Kondo lattice system YbRh 2Si 2. J Phys Condens Matter 2021; 33:205601. [PMID: 33561846 DOI: 10.1088/1361-648x/abe479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 02/09/2021] [Indexed: 06/12/2023]
Abstract
The heavy-fermion behavior in intermetallic compounds manifests itself in a quenching of local magnetic moments by developing Kondo spin-singlet many-body states combined with a drastic increase of the effective mass of conduction electrons, which occurs below the lattice Kondo temperatureTK. This behavior is caused by interactions between the strongly localized 4felectrons and itinerant electrons. A controversially discussed question in this context is how the localized electronic states contribute to the Fermi surface upon changing the temperature. One expects that hybridization between the local moments and the itinerant electrons leads to a transition from a small Fermi surface in a non-coherent regime at high temperatures to a large Fermi surface once the coherent Kondo lattice regime is realized belowTK. We demonstrate, using hard x-ray angle-resolved photoemission spectroscopy that the electronic structure of the prototypical heavy fermion compound YbRh2Si2changes with temperature between 100 and 200 K, i.e. far above the Kondo temperature,TK= 25 K, of this system. Our results suggest a transition from a small to a large Fermi surface with decreasing temperature. This result is inconsistent with the prediction of the dynamical mean-field periodic Anderson model and supports the idea of an independent energy scale governing the change of band dispersion.
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Affiliation(s)
- S Y Agustsson
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz, Germany
| | - S V Chernov
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz, Germany
| | - K Medjanik
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz, Germany
| | - S Babenkov
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz, Germany
| | - O Fedchenko
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz, Germany
| | - D Vasilyev
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz, Germany
| | - C Schlueter
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - A Gloskovskii
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Yu Matveyev
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - K Kliemt
- Physikalisches Institut, Goethe Universität Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
| | - C Krellner
- Physikalisches Institut, Goethe Universität Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
| | - J Demsar
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz, Germany
| | - G Schönhense
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz, Germany
| | - H-J Elmers
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz, Germany
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6
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Elmers HJ, Chernov SV, D'Souza SW, Bommanaboyena SP, Bodnar SY, Medjanik K, Babenkov S, Fedchenko O, Vasilyev D, Agustsson SY, Schlueter C, Gloskovskii A, Matveyev Y, Strocov VN, Skourski Y, Šmejkal L, Sinova J, Minár J, Kläui M, Schönhense G, Jourdan M. Néel Vector Induced Manipulation of Valence States in the Collinear Antiferromagnet Mn 2Au. ACS Nano 2020; 14:17554-17564. [PMID: 33236903 DOI: 10.1021/acsnano.0c08215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The coupling of real and momentum space is utilized to tailor electronic properties of the collinear metallic antiferromagnet Mn2Au by aligning the real space Néel vector indicating the direction of the staggered magnetization. Pulsed magnetic fields of 60 T were used to orient the sublattice magnetizations of capped epitaxial Mn2Au(001) thin films perpendicular to the applied field direction by a spin-flop transition. The electronic structure and its corresponding changes were investigated by angular-resolved photoemission spectroscopy with photon energies in the vacuum-ultraviolet, soft, and hard X-ray range. The results reveal an energetic rearrangement of conduction electrons propagating perpendicular to the Néel vector. They confirm previous predictions on the origin of the Néel spin-orbit torque and anisotropic magnetoresistance in Mn2Au and reflect the combined antiferromagnetic and spin-orbit interaction in this compound leading to inversion symmetry breaking.
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Affiliation(s)
- H J Elmers
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S V Chernov
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S W D'Souza
- New Technologies-Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic
| | - S P Bommanaboyena
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S Yu Bodnar
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - K Medjanik
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S Babenkov
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - O Fedchenko
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - D Vasilyev
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S Y Agustsson
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - C Schlueter
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - A Gloskovskii
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Yu Matveyev
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
| | - Y Skourski
- Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - L Šmejkal
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
- Institute of Physics Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - J Sinova
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
- Institute of Physics Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - J Minár
- New Technologies-Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic
| | - M Kläui
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - G Schönhense
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - M Jourdan
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
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7
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Schönhense G, Babenkov S, Vasilyev D, Elmers HJ, Medjanik K. Single-hemisphere photoelectron momentum microscope with time-of-flight recording. Rev Sci Instrum 2020; 91:123110. [PMID: 33379996 DOI: 10.1063/5.0024074] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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8
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Bühlmann K, Gort R, Fognini A, Däster S, Holenstein S, Hartmann N, Zemp Y, Salvatella G, Michlmayr TU, Bähler T, Kutnyakhov D, Medjanik K, Schönhense G, Vaterlaus A, Acremann Y. Compact setup for spin-, time-, and angle-resolved photoemission spectroscopy. Rev Sci Instrum 2020; 91:063001. [PMID: 32611013 DOI: 10.1063/5.0004861] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 05/16/2020] [Indexed: 06/11/2023]
Abstract
We present a compact setup for spin-, time-, and angle-resolved photoemission spectroscopy. A 10 kHz titanium sapphire laser system delivers pulses of 20 fs duration, which drive a high harmonic generation-based source for ultraviolet photons at 21 eV for photoemission. The same laser also excites the sample for pump-probe experiments. Emitted electrons pass through a hemispherical energy analyzer and a spin-filtering element. The latter is based on spin-polarized low-energy electron diffraction on an Au-passivated iridium crystal. The performance of the measurement system is discussed in terms of the resolution and efficiency of the spin filter, which are higher than those for Mott-based techniques.
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Affiliation(s)
- K Bühlmann
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - R Gort
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - A Fognini
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - S Däster
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - S Holenstein
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - N Hartmann
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - Y Zemp
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - G Salvatella
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - T U Michlmayr
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - T Bähler
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - D Kutnyakhov
- Institute of Physics, Johannes Gutenberg University of Mainz, 55128 Mainz, Germany
| | - K Medjanik
- Institute of Physics, Johannes Gutenberg University of Mainz, 55128 Mainz, Germany
| | - G Schönhense
- Institute of Physics, Johannes Gutenberg University of Mainz, 55128 Mainz, Germany
| | - A Vaterlaus
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - Y Acremann
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
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9
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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. Rev Sci Instrum 2020; 91:013109. [PMID: 32012554 DOI: 10.1063/1.5118777] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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10
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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. J Synchrotron Radiat 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] [What about the content of this article? (0)] [Affiliation(s)] [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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11
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Nepijko SA, Chernov SV, Cheshko IV, Shabelnyk YM, Protsenko IY, Schönhense G. Matching emission centers of electrons and photons in current-carrying silver nanoparticle films. Appl Opt 2019; 58:2382-2384. [PMID: 31044939 DOI: 10.1364/ao.58.002382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 02/18/2019] [Indexed: 06/09/2023]
Abstract
Current flow through a nanoparticle film (two-dimensional ensemble of small tunnel-coupled metal particles on a dielectric substrate) is accompanied by electron and photon emission. It has a localized character (originates from emission centers). With an increase in applied voltage, the number of emission centers increases, and with further increase, some of them may burn out. In dark conditions, photon emission centers are visible with a bare eye. To visualize electron emission centers, emission electron microscopy is used. The conducted measurements allow comparison of the number and relative positions of electron and photon emission centers. It is shown that electrons and photons are emitted from the same centers.
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12
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Schlueter C, Gloskovskii A, Ederer K, Piec S, Sing M, Claessen R, Wiemann C, Schneider C, Medjanik K, Schönhense G, Amann P, Nilsson A, Drube W. New HAXPES Applications at PETRA III. ACTA ACUST UNITED AC 2018. [DOI: 10.1080/08940886.2018.1483656] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- C. Schlueter
- Photon Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - A. Gloskovskii
- Photon Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - K. Ederer
- Photon Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - S. Piec
- Photon Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - M. Sing
- Physikalisches Institut and Röntgen Center for Complex Materials Systems, Universität Würzburg, Würzburg, Germany
| | - R. Claessen
- Physikalisches Institut and Röntgen Center for Complex Materials Systems, Universität Würzburg, Würzburg, Germany
| | - C. Wiemann
- Peter Grünberg Institut, Jülich, Germany
| | | | - K. Medjanik
- Institut für Physik, Johannes Gutenberg-Universität, Mainz, Germany
| | - G. Schönhense
- Institut für Physik, Johannes Gutenberg-Universität, Mainz, Germany
| | - P. Amann
- Department of Physics, AlbaNova University Center, Stockholm University, Stockholm, Sweden
| | - A. Nilsson
- Department of Physics, AlbaNova University Center, Stockholm University, Stockholm, Sweden
| | - W. Drube
- Photon Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
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13
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Schönhense G, Medjanik K, Chernov S, Kutnyakhov D, Fedchenko O, Ellguth M, Vasilyev D, Zaporozhchenko-Zymaková A, Panzer D, Oelsner A, Tusche C, Schönhense B, Braun J, Minár J, Ebert H, Viefhaus J, Wurth W, Elmers HJ. Spin-filtered time-of-flight k-space microscopy of Ir - Towards the "complete" photoemission experiment. Ultramicroscopy 2017; 183:19-29. [PMID: 28705441 DOI: 10.1016/j.ultramic.2017.06.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 06/16/2017] [Accepted: 06/28/2017] [Indexed: 11/28/2022]
Abstract
The combination of momentum microscopy (high resolution imaging of the Fourier plane) with an imaging spin filter has recently set a benchmark in k-resolution and spin-detection efficiency. Here we show that the degree of parallelization can be further increased by time-of-flight energy recording. On the quest towards maximum information (in earlier work termed "complete" photoemission experiment) we have studied the prototypical high-Z fcc metal iridium. Large partial bandgaps and strong spin-orbit interaction lead to a sequence of spin-polarized surface resonances. Soft X-rays give access to the 4D spectral density function ρ (EB,kx,ky,kz) weighted by the photoemission cross section. The Fermi surface and all other energy isosurfaces, Fermi velocity distribution vF(kF), electron or hole conductivity, effective mass and inner potential can be obtained from the multi-dimensional array ρ by simple algorithms. Polarized light reveals the linear and circular dichroism texture in a simple manner and an imaging spin filter exposes the spin texture. One-step photoemission calculations are in fair agreement with experiment. Comparison of the Bloch spectral function with photoemission calculations uncovers that the observed high spin polarization of photoelectrons from bulk bands originates from the photoemission step and is not present in the initial state.
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Affiliation(s)
- G Schönhense
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany.
| | - K Medjanik
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany
| | - S Chernov
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany
| | - D Kutnyakhov
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany; DESY, Hamburg, Germany
| | - O Fedchenko
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany
| | - M Ellguth
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany
| | - D Vasilyev
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany
| | | | - D Panzer
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany; Surface Concept GmbH, Am Sägewerk 23a, 55124 Mainz, Germany
| | - A Oelsner
- Surface Concept GmbH, Am Sägewerk 23a, 55124 Mainz, Germany
| | - C Tusche
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - B Schönhense
- Department of Bioengineering, Imperial College London, UK
| | - J Braun
- Department Chemie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - J Minár
- Department Chemie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany; New Technologies-Research Center, University of West Bohemia, Pilsen, Czech Republic
| | - H Ebert
- Department Chemie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | | | - W Wurth
- DESY, Hamburg, Germany; Physics Department and CFEL, University of Hamburg, Germany
| | - H J Elmers
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55099 Mainz, Germany
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14
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Elmers HJ, Kutnyakhov D, Chernov SV, Medjanik K, Fedchenko O, Zaporozhchenko-Zymakova A, Ellguth M, Tusche C, Viefhaus J, Schönhense G. Hosting of surface states in spin-orbit induced projected bulk band gaps of W(1 1 0) and Ir(1 1 1). J Phys Condens Matter 2017; 29:255001. [PMID: 28537224 DOI: 10.1088/1361-648x/aa7173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Spin-momentum locking of surface states has attracted great interest in recent years due to envisioned technological applications in the field of spintronics. Normal metal surfaces like W(1 1 0) and Ir(1 1 1) show surface states with energy dispersions and spin-polarization textures, which are reminiscent of topologically non-trivial surface states. In order to understand this phenomenon the connection of bulk and surface states has to be explored. Using time-of-flight momentum microscopy with soft x-ray excitation, we present a comprehensive analysis of the bulk bands of W and Ir. Surface states are determined by the same method with photon excitation in the vacuum ultraviolet region. The superposition of both spectral densities reveals the hosting of surface states within the gap structure of bulk bands projected on the surface Brillouin zone. Quantitative differences in the extension of experimental and theoretical local band gaps indicate an underestimation of electron correlation effects in theory.
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Affiliation(s)
- H J Elmers
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
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15
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Medjanik K, Fedchenko O, Chernov S, Kutnyakhov D, Ellguth M, Oelsner A, Schönhense B, Peixoto TRF, Lutz P, Min CH, Reinert F, Däster S, Acremann Y, Viefhaus J, Wurth W, Elmers HJ, Schönhense G. Direct 3D mapping of the Fermi surface and Fermi velocity. Nat Mater 2017; 16:615-621. [PMID: 28272500 DOI: 10.1038/nmat4875] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 02/03/2017] [Indexed: 05/13/2023]
Abstract
We performed a full mapping of the bulk electronic structure including the Fermi surface and Fermi-velocity distribution vF(kF) of tungsten. The 4D spectral function ρ(EB; k) in the entire bulk Brillouin zone and 6 eV binding-energy (EB) interval was acquired in ∼3 h thanks to a new multidimensional photoemission data-recording technique (combining full-field k-microscopy with time-of-flight parallel energy recording) and the high brilliance of the soft X-rays used. A direct comparison of bulk and surface spectral functions (taken at low photon energies) reveals a time-reversal-invariant surface state in a local bandgap in the (110)-projected bulk band structure. The surface state connects hole and electron pockets that would otherwise be separated by an indirect local bandgap. We confirmed its Dirac-like spin texture by spin-filtered momentum imaging. The measured 4D data array enables extraction of the 3D dispersion of all bands, all energy isosurfaces, electron velocities, hole or electron conductivity, effective mass and inner potential by simple algorithms without approximations. The high-Z bcc metals with large spin-orbit-induced bandgaps are discussed as candidates for topologically non-trivial surface states.
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Affiliation(s)
- K Medjanik
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
| | - O Fedchenko
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
| | - S Chernov
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
| | - D Kutnyakhov
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
- DESY Photon Science, Notkestraße 85, 22607 Hamburg, Germany
| | - M Ellguth
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
| | - A Oelsner
- Surface Concept GmbH, Am Sägewerk 23a, 55124 Mainz, Germany
| | - B Schönhense
- Department of Bioengineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - T R F Peixoto
- Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany
| | - P Lutz
- Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany
| | - C-H Min
- Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany
| | - F Reinert
- Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany
| | - S Däster
- Laboratorium für Festkörperphysik, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - Y Acremann
- Laboratorium für Festkörperphysik, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - J Viefhaus
- DESY Photon Science, Notkestraße 85, 22607 Hamburg, Germany
| | - W Wurth
- DESY Photon Science, Notkestraße 85, 22607 Hamburg, Germany
- Physics Department and Center for Free-Electron Laser Science, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - H J Elmers
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
| | - G Schönhense
- Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany
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16
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Borek S, Braun J, Minár J, Kutnyakhov D, Elmers HJ, Schönhense G, Ebert H. Determination of surface and interface magnetic properties for the multiferroic heterostructure Co/BaTiO3 using spleed and arpes. J Phys Condens Matter 2016; 28:436004. [PMID: 27603180 DOI: 10.1088/0953-8984/28/43/436004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Co/BaTiO3(0 0 1) is one of the most interesting multiferroic heterostructures as it combines different ferroic phases, setting this way the fundamentals for innovative technical applications. Various theoretical approaches have been applied to investigate the electronic and magnetic properties of Co/BaTiO3(0 0 1). Here we determine the magnetic properties of 3 ML Co/BaTiO3 by calculating spin-polarized electron diffraction as well as angle-resolved photoemission spectra, with both methods being well established as surface sensitive techniques. Furthermore, we discuss the impact of altering the BaTiO3 polarization on the spectra and ascribe the observed changes to characteristic details of the electronic structure.
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Affiliation(s)
- St Borek
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstraße 5-13, 81377 München, Germany
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17
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Medjanik K, Chernenkaya A, Kozina X, Nepijko SA, Öhrwall G, Foury-Leylekian P, Alemany P, Schönhense G, Canadell E, Pouget JP. Near-Edge X-ray Absorption Fine Structure Investigation of the Quasi-One-Dimensional Organic Conductor (TMTSF)2PF6. J Phys Chem A 2016; 120:8574-8583. [DOI: 10.1021/acs.jpca.6b07536] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- K. Medjanik
- Lund University, MAX IV Laboratory, 22100 Lund, Sweden
| | - A. Chernenkaya
- Institut
für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany
- Graduate
School of Materials Science in Mainz, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - X. Kozina
- Institut
für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - S. A. Nepijko
- Institut
für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - G. Öhrwall
- Lund University, MAX IV Laboratory, 22100 Lund, Sweden
| | - P. Foury-Leylekian
- Laboratoire
de Physique des Solides, Université Paris-Sud, CNRS UMR 8502, 91405 Orsay, France
| | - P. Alemany
- Departament
de Ciència de Materials i Química Física and
Institut de Química Teórica i Computacional (IQTCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain
| | - G. Schönhense
- Institut
für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - E. Canadell
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Spain
| | - J.-P. Pouget
- Laboratoire
de Physique des Solides, Université Paris-Sud, CNRS UMR 8502, 91405 Orsay, France
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18
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Chernenkaya A, Morherr A, Backes S, Popp W, Witt S, Kozina X, Nepijko SA, Bolte M, Medjanik K, Öhrwall G, Krellner C, Baumgarten M, Elmers HJ, Schönhense G, Jeschke HO, Valentí R. Microscopic origin of the charge transfer in single crystals based on thiophene derivatives: A combined NEXAFS and density functional theory approach. J Chem Phys 2016; 145:034702. [PMID: 27448899 DOI: 10.1063/1.4958659] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- A. Chernenkaya
- Graduate School Materials Science in Mainz, 55128 Mainz, Germany
- Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - A. Morherr
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt am Main, Germany
| | - S. Backes
- Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt am Main, Germany
| | - W. Popp
- Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt am Main, Germany
| | - S. Witt
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt am Main, Germany
| | - X. Kozina
- Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - S. A. Nepijko
- Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - M. Bolte
- Institut für Anorganische Chemie, Goethe-Universität, 60438 Frankfurt am Main, Germany
| | - K. Medjanik
- MAX-IV Laboratory, Lund University, 22100 Lund, Sweden
| | - G. Öhrwall
- MAX-IV Laboratory, Lund University, 22100 Lund, Sweden
| | - C. Krellner
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt am Main, Germany
| | - M. Baumgarten
- Max-Planck-Institut für Polymerforschung, 55021 Mainz, Germany
| | - H. J. Elmers
- Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - G. Schönhense
- Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - H. O. Jeschke
- Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt am Main, Germany
| | - R. Valentí
- Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt am Main, Germany
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19
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Nepijko SA, Chernenkaya A, Medjanik K, Chernov SV, Sapozhnik AA, Odnodvorets LV, Protsenko IY, Schulze W, Ertl G, Schönhense G. Spectral Measurement of Photon Emission from Individual Gold Nanoparticles Using Scanning Tunneling Microscopy. ACTA ACUST UNITED AC 2016. [DOI: 10.21272/jnep.8(2).02039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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20
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Chernov SV, Medjanik K, Tusche C, Kutnyakhov D, Nepijko SA, Oelsner A, Braun J, Minár J, Borek S, Ebert H, Elmers HJ, Kirschner J, Schönhense G. Anomalous d-like surface resonances on Mo(110) analyzed by time-of-flight momentum microscopy. Ultramicroscopy 2015; 159 Pt 3:453-63. [PMID: 26363904 DOI: 10.1016/j.ultramic.2015.07.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 05/26/2015] [Accepted: 07/16/2015] [Indexed: 11/28/2022]
Abstract
The electronic surface states on Mo(110) have been investigated using time-of-flight momentum microscopy with synchrotron radiation (hν=35 eV). This novel angle-resolved photoemission approach yields a simultaneous acquisition of the E-vs-k spectral function in the full surface Brillouin zone and several eV energy interval. (kx,ky,EB)-maps with 3.4 Å(-1) diameter reveal a rich structure of d-like surface resonances in the spin-orbit induced partial band gap. Calculations using the one-step model in its density matrix formulation predict an anomalous state with Dirac-like signature and Rashba spin texture crossing the bandgap at Γ¯ and EB=1.2 eV. The experiment shows that the linear dispersion persists away from the Γ¯-point in an extended energy- and k∥-range. Analogously to a similar state previously found on W(110) the dispersion is linear along H¯-Γ¯-H¯ and almost zero along N¯-Γ¯-N¯. The similarity is surprising since the spin-orbit interaction is 5 times smaller in Mo. A second point with unusual topology is found midway between Γ¯ and N¯. Band symmetries are probed by linear dichroism.
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Affiliation(s)
- S V Chernov
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - K Medjanik
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - C Tusche
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany
| | - D Kutnyakhov
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - S A Nepijko
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - A Oelsner
- Surface Concept GmbH, Am Sägewerk 23A, D-55124 Mainz, Germany
| | - J Braun
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, D-81377 München, Germany
| | - J Minár
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, D-81377 München, Germany; New Technologies-Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic
| | - S Borek
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, D-81377 München, Germany
| | - H Ebert
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, D-81377 München, Germany
| | - H J Elmers
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - J Kirschner
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany
| | - G Schönhense
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany.
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21
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Schönhense G, Medjanik K, Tusche C, de Loos M, van der Geer B, Scholz M, Hieke F, Gerken N, Kirschner J, Wurth W. Correction of the deterministic part of space-charge interaction in momentum microscopy of charged particles. Ultramicroscopy 2015; 159 Pt 3:488-96. [PMID: 26051657 DOI: 10.1016/j.ultramic.2015.05.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 05/13/2015] [Accepted: 05/15/2015] [Indexed: 10/23/2022]
Abstract
Ultrahigh spectral brightness femtosecond XUV and X-ray sources like free electron lasers (FEL) and table-top high harmonics sources (HHG) offer fascinating experimental possibilities for analysis of transient states and ultrafast electron dynamics. For electron spectroscopy experiments using illumination from such sources, the ultrashort high-charge electron bunches experience strong space-charge interactions. The Coulomb interactions between emitted electrons results in large energy shifts and severe broadening of photoemission signals. We propose a method for a substantial reduction of the effect by exploiting the deterministic nature of space-charge interaction. The interaction of a given electron with the average charge density of all surrounding electrons leads to a rotation of the electron distribution in 6D phase space. Momentum microscopy gives direct access to the three momentum coordinates, opening a path for a correction of an essential part of space-charge interaction. In a first experiment with a time-of-flight momentum microscope using synchrotron radiation at BESSY, the rotation in phase space became directly visible. In a separate experiment conducted at FLASH (DESY), the energy shift and broadening of the photoemission signals were quantified. Finally, simulations of a realistic photoemission experiment including space-charge interaction reveals that a gain of an order of magnitude in resolution is possible using the correction technique presented here.
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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
| | - C Tusche
- Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle, Germany
| | - M de Loos
- Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven, The Netherlands
| | - B van der Geer
- Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven, The Netherlands
| | - M Scholz
- Physics Department and Center for Free-Electron Laser Science, Univ. Hamburg, 22761 Hamburg, Germany
| | - F Hieke
- Physics Department and Center for Free-Electron Laser Science, Univ. Hamburg, 22761 Hamburg, Germany
| | - N Gerken
- Physics Department and Center for Free-Electron Laser Science, Univ. Hamburg, 22761 Hamburg, Germany
| | - J Kirschner
- Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle, Germany
| | - W Wurth
- Physics Department and Center for Free-Electron Laser Science, Univ. Hamburg, 22761 Hamburg, Germany; DESY Photon Science, 22607 Hamburg, Germany
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22
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Medjanik K, Chernenkaya A, Nepijko SA, Öhrwall G, Foury-Leylekian P, Alemany P, Canadell E, Schönhense G, Pouget JP. Donor–anion interactions at the charge localization and charge ordering transitions of (TMTTF)2AsF6 probed by NEXAFS. Phys Chem Chem Phys 2015; 17:19202-14. [DOI: 10.1039/c5cp02902c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Detection of the charge localization and charge ordering transitions of (TMTTF)2AsF6 at Tρ ≈ 230 K and TCO ≈ 102 K, respectively.
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Affiliation(s)
- K. Medjanik
- Lund University
- MAX IV Laboratory
- 22100 Lund
- Sweden
| | - A. Chernenkaya
- Institut für Physik
- Johannes Gutenberg-Universität
- 55099 Mainz
- Germany
- Graduate School Materials Science in Mainz
| | - S. A. Nepijko
- Institut für Physik
- Johannes Gutenberg-Universität
- 55099 Mainz
- Germany
| | - G. Öhrwall
- Lund University
- MAX IV Laboratory
- 22100 Lund
- Sweden
| | - P. Foury-Leylekian
- Laboratoire de Physique des Solides
- Université Paris-Sud
- 91405 Orsay
- France
| | - P. Alemany
- Departament de Química Física and Institut de Química Teórica i Computacional (IQTCUB)
- Universitat de Barcelona
- 08028 Barcelona
- Spain
| | - E. Canadell
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC)
- 08193 Bellaterra
- Spain
| | - G. Schönhense
- Institut für Physik
- Johannes Gutenberg-Universität
- 55099 Mainz
- Germany
| | - J.-P. Pouget
- Laboratoire de Physique des Solides
- Université Paris-Sud
- 91405 Orsay
- France
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23
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Kutnyakhov D, Lushchyk P, Fognini A, Perriard D, Kolbe M, Medjanik K, Fedchenko E, Nepijko SA, Elmers HJ, Salvatella G, Stieger C, Gort R, Bähler T, Michlmayer T, Acremann Y, Vaterlaus A, Giebels F, Gollisch H, Feder R, Tusche C, Krasyuk A, Kirschner J, Schönhense G. Imaging spin filter for electrons based on specular reflection from iridium (001). Ultramicroscopy 2013; 130:63-9. [PMID: 23639852 DOI: 10.1016/j.ultramic.2013.03.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2012] [Revised: 03/15/2013] [Accepted: 03/18/2013] [Indexed: 11/18/2022]
Abstract
As Stern-Gerlach type spin filters do not work with electrons, spin analysis of electron beams is accomplished by spin-dependent scattering processes based on spin-orbit or exchange interaction. Existing polarimeters are single-channel devices characterized by an inherently low figure of merit (FoM) of typically 10⁻⁴-10⁻³. This single-channel approach is not compatible with parallel imaging microscopes and also not with modern electron spectrometers that acquire a certain energy and angular interval simultaneously. We present a novel type of polarimeter that can transport a full image by making use of k-parallel conservation in low-energy electron diffraction. We studied specular reflection from Ir (001) because this spin-filter crystal provides a high analyzing power combined with a "lifetime" in UHV of a full day. One good working point is centered at 39 eV scattering energy with a broad maximum of 5 eV usable width. A second one at about 10 eV shows a narrower profile but much higher FoM. A relativistic layer-KKR SPLEED calculation shows good agreement with measurements.
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Affiliation(s)
- D Kutnyakhov
- Johannes Gutenberg-Universität, Institut für Physik, 55099 Mainz, Germany
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24
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Nepijko SA, Fedchenko O, Chernov SV, Schönhense G. Growth and defect studies of CdTe particles. Crystal Research and Technology 2013. [DOI: 10.1002/crat.201200490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- S. A. Nepijko
- Institute of Physics; University of Mainz; Staudingerweg 7; 55128 Mainz; Germany
| | - O. Fedchenko
- Sumy State University; Rimsky-Korsakov Str. 2; 40007 Sumy; C.I.S./Ukraine
| | - S. V. Chernov
- Institute of Physics; University of Mainz; Staudingerweg 7; 55128 Mainz; Germany
| | - G. Schönhense
- Institute of Physics; University of Mainz; Staudingerweg 7; 55128 Mainz; Germany
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25
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Klanke J, Rentschler E, Medjanik K, Kutnyakhov D, Schönhense G, Krasnikov S, Shvets IV, Schuppler S, Nagel P, Merz M, Elmers HJ. Beyond the Heisenberg model: anisotropic exchange interaction between a Cu-tetraazaporphyrin monolayer and Fe3O4(100). Phys Rev Lett 2013; 110:137202. [PMID: 23581364 DOI: 10.1103/physrevlett.110.137202] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Indexed: 06/02/2023]
Abstract
The exchange coupling of a single spin localized at the central ion of Cu-tetraazaporphyrin on a magnetite(100) surface has been studied using x-ray magnetic circular dichroism (XMCD). Sum rule analysis of the XMCD spectra results in Cu spin and orbital magnetic moments as a function of the applied external field at low temperatures (20 K). The exchange coupling is positive for magnetization direction perpendicular to the surface (ferromagnetic) while it is negative for in-plane magnetization direction (antiferromagnetic). We attribute the anisotropy of the Heisenberg exchange coupling to an orbitally dependent exchange Hamiltonian.
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Affiliation(s)
- J Klanke
- Institut für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
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26
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Graivoronska KO, Klimenkov M, Solonin YM, Nepijko SA, Schönhense G. Detailed study of defects in thin fullerite films. Cryst Res Technol 2012. [DOI: 10.1002/crat.201200304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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27
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Kolbe M, Lushchyk P, Petereit B, Elmers HJ, Schönhense G, Oelsner A, Tusche C, Kirschner J. Highly efficient multichannel spin-polarization detection. Phys Rev Lett 2011; 107:207601. [PMID: 22181775 DOI: 10.1103/physrevlett.107.207601] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Indexed: 05/31/2023]
Abstract
Since the original work by Mott, the low efficiency of electron spin polarimeters, remaining orders of magnitude behind optical polarimeters, has prohibited many fundamental experiments. Here we report a solution to this problem using a novel concept of multichannel spin-polarization analysis that provides a stunning increase in efficiency by 4 orders of magnitude. This improvement was demonstrated in a setup using a hemispherical electron energy analyzer. An imaging setup proved the principal capability of resolving more than 10(5) data points in parallel.
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Affiliation(s)
- M Kolbe
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Germany.
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28
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Schneider C, Frömter R, Ziethen C, Swiech W, Brookes N, Schönhense G, Kirschner J. Magnetic Domain Imaging with a Photoemission Microscope. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-475-381] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTPhotoelectron emission microscopy (PEEM) has proven to be a versatile analytical technique in surface science. When operated with circularly polarized light in the soft x-ray regime, however, photoemission microscopy offers a unique combination of magnetic and chemical information. Exploiting the high brilliance and circular polarization available at a helical undulator beamline, the lateral resolution in the imaging of magnetic domain structures may be pushed well into the sub-micrometer range. Using a newly designed photoemission microscope we show that under these circumstances not only domains, but also domain walls can be selectively investigated. The high sensitivity of the technique yields a sizable magnetic contrast even from magnetic films as thin as a fraction of a single monolayer. The combination of chemical selectivity and information depth is successfully employed to investigate the magnetic behavior of buried layers and covered surfaces. This approach offers a convenient access to magnetic coupling phenomena in magnetic sandwiches.
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29
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Nepijko SA, Krasyuk A, Oelsner A, Schneider CM, Schönhense G. Quantitative measurements of magnetic stray field dynamics of Permalloy particles in a photoemission electron microscopy. J Microsc 2010; 242:216-20. [PMID: 21155993 DOI: 10.1111/j.1365-2818.2010.03472.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
By example of a Permalloy particle (40 × 40 μm(2) size, 30 nm thickness) we demonstrate a procedure to quantitatively investigate the dynamics of magnetic stray fields during ultrafast magnetization reversal. The measurements have been performed in a time-resolving photoemission electron microscope using the X-ray magnetic circular dichroism. In the particle under investigation, we have observed a flux-closure-dominated magnetic ground structure, minimizing the magnetic stray field outside the sample. A fast magnetic field pulse introduced changes in the micromagnetic structure accompanied with an incomplete flux closure. As a result, stray fields arise along the edges of domains, which cause a change of contrast and an image deformation of the particles geometry (curvature of its edge). The magnetic stray fields are calculated from a deformation of the X-ray magnetic circular dichroism (XMCD) images taken after the magnetic field pulse in a 1 ns interval. These measurements reveal a decrease of magnetic stray fields with time. An estimate of the lower limit of the domain wall velocity yields about 2 × 10(3) m s(-1).
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Affiliation(s)
- S A Nepijko
- Institute of Physics, University of Mainz, Mainz, Germany.
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30
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Medjanik K, Kutnyakhov D, Nepijko SA, Schönhense G, Naghavi S, Alijani V, Felser C, Koch N, Rieger R, Baumgarten M, Müllen K. Electronic structure of large disc-type donors and acceptors. Phys Chem Chem Phys 2010; 12:7184-93. [DOI: 10.1039/b926999a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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31
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Schneider C, Krug I, Müller M, Matthes F, Kaiser A, Wiemann C, Cramm S, Elmers HJ, Wegelin F, Krasyuk A, Nepijko S, Schönhense G. Investigating spintronics thin film systems with synchrotron radiation. Radiat Phys Chem Oxf Engl 1993 2009. [DOI: 10.1016/j.radphyschem.2009.02.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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32
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Hild K, Maul J, Schönhense G, Elmers HJ, Amft M, Oppeneer PM. Magnetic circular dichroism in two-photon photoemission. Phys Rev Lett 2009; 102:057207. [PMID: 19257547 DOI: 10.1103/physrevlett.102.057207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Indexed: 05/27/2023]
Abstract
We report the observation of magnetic circular dichroism (MCD) in two-photon photoemission (2PPE). The Heusler alloys Ni2MnGa and Co2FeSi were investigated by excitation with femtosecond laser light, showing MCD asymmetries of A=(3.5+/-0.5)x10;{-3} for Ni2MnGa and of A=(2.1+/-1.0)x10;{-3} for Co2FeSi, respectively. A theoretical explanation is provided based on local spin-density calculations for the magnetic dichroic response; the computed 2PPE MCD agrees well with the experiment. The observed 2PPE magnetic contrast represents an interesting alternative for future time-resolved photoemission studies on surface magnetism practicable in the laboratory.
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Affiliation(s)
- K Hild
- Institut für Physik, Staudinger Weg 7, Universität Mainz, D-55128 Mainz, Germany
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33
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Hild K, Maul J, Meng T, Kallmayer M, Schönhense G, Elmers HJ, Ramos R, Arora SK, Shvets IV. Optical magnetic circular dichroism in threshold photoemission from a magnetite thin film. J Phys Condens Matter 2008; 20:235218. [PMID: 21694309 DOI: 10.1088/0953-8984/20/23/235218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Threshold photoemission excited by polarization-modulated ultraviolet femtosecond laser light is exploited for phase-sensitive detection of magnetic circular dichroism (MCD) for a magnetite thin film. Magnetite (Fe(3)O(4)) shows a magnetic circular dichroism of ∼(4.5 ± 0.3) × 10(-3) for perpendicularly incident circularly polarized light and a magnetization vector switched parallel and antiparallel to the helicity vector by an external magnetic field. The asymmetry in threshold photoemission is discussed in comparison to the magneto-optical Kerr effect. The optical MCD contrast in threshold photoemission will provide a basis for future laboratory photoemission studies on magnetic surfaces.
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Affiliation(s)
- K Hild
- Institut für Physik, Johannes Gutenberg-Universität, Staudinger Weg 7, D-55128 Mainz, Germany
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Schönhense G, Elmers H, Nepijko S, Schneider C. Time-Resolved Photoemission Electron Microscopy. Advances in Imaging and Electron Physics 2006. [DOI: 10.1016/s1076-5670(05)42003-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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35
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Schönhense G, Elmers HJ. PEEM with high time resolution—imaging of transient processes and novel concepts of chromatic and spherical aberration correction. SURF INTERFACE ANAL 2006. [DOI: 10.1002/sia.2433] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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36
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Krasyuk A, Wegelin F, Nepijko SA, Elmers HJ, Schönhense G, Bolte M, Schneider CM. Self-trapping of magnetic oscillation modes in Landau flux-closure structures. Phys Rev Lett 2005; 95:207201. [PMID: 16384091 DOI: 10.1103/physrevlett.95.207201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Indexed: 05/05/2023]
Abstract
We investigated the magnetodynamics in rectangular Permalloy platelets by means of time-resolved x-ray photoemission microscopy. 10 nm thick platelets of size 16 x 32 microm were excited by an oscillatory field along the short side of the sample with a fundamental frequency of 500 MHz and considerable contributions of higher harmonics. Under the influence of the oscillatory field, the Néel wall in the initial classical Landau pattern shifts away from the center, corresponding to an induced magnetic moment perpendicular to the exciting field. This phenomenon is explained by a self-trapping effect of the dominating spin-wave mode when the system is excited just below the resonance frequency. The basic driving mechanism is the maximization of entropy.
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Affiliation(s)
- A Krasyuk
- Institut für Physik, Universität Mainz, D-55128 Mainz, Germany
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37
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Cinchetti M, Gloskovskii A, Nepjiko SA, Schönhense G, Rochholz H, Kreiter M. Photoemission electron microscopy as a tool for the investigation of optical near fields. Phys Rev Lett 2005; 95:047601. [PMID: 16090841 DOI: 10.1103/physrevlett.95.047601] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Indexed: 05/03/2023]
Abstract
Photoemission electron microscopy was used to image the electrons photoemitted from specially tailored Ag nanoparticles deposited on a Si substrate (with its native oxide SiO(x)). Photoemission was induced by illumination with a Hg UV lamp (photon energy cutoff homega(UV) = 5.0 eV, wavelength lambda(UV) = 250 nm) and with a Ti:sapphire femtosecond laser (homega(l) = 3.1 eV, lambda(l) = 400 nm, pulse width below 200 fs), respectively. While homogeneous photoelectron emission from the metal is observed upon illumination at energies above the silver plasmon frequency, at lower photon energies the emission is localized at tips of the structure. This is interpreted as a signature of the local electrical field therefore providing a tool to map the optical near field with the resolution of emission electron microscopy.
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Affiliation(s)
- M Cinchetti
- Johannes Gutenberg-Universität, Institut für Physik, Mainz, Germany
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38
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Wurmehl S, Fecher GH, Kandpal HC, Kroth K, Elmers HJ, Schönhense G, Felser C, Morais J, Hwu Y, Klauser R. Charakterisierung von dotierten Heusler-Verbindungen: Co2Cr1−xFexAl. Z Anorg Allg Chem 2004. [DOI: 10.1002/zaac.200470154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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39
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Nepijko SA, Gloskovskii A, Sedov NN, Schönhense G. Measurement of the electric field distribution and potentials on the object surface in an emission electron microscope without restriction of the electron beams. J Microsc 2003; 211:89-94. [PMID: 12839555 DOI: 10.1046/j.1365-2818.2003.01199.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
An emission electron microscope without restriction of the electron beams was used to visualize and measure the distribution of electric fields and potentials on the surface under study. Investigations of this kind can be performed in an emission electron microscope without any aperture diaphragm. The potentialities of this method have been demonstrated using measurements with a silicon p-n junction to which a voltage has been applied in the reverse direction. The quantitative analysis becomes more complicated if the specimen is characterized by a heterogeneous intensity distribution of the electron emission from different areas of its surface. In the latter case two images obtained at different accelerating voltages (i.e. different voltages of the microscope extractor) provide the information necessary for an analysis of electric field and potential distributions.
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Affiliation(s)
- S A Nepijko
- Institute of Physics, University Mainz, Staudingerweg 7, 55099 Mainz, Germany.
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40
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Kuznetsov VV, Cherepkov NA, Fecher GH, Schönhense G. Angular distributions and dichroism of photoelectrons ejected from fixed-in-space molecules of definite symmetry: Application to the C2v symmetry group. J Chem Phys 2002. [DOI: 10.1063/1.1507586] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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41
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Abstract
An emission electron microscope was used for visualization and measurement of the distribution of electric fields and potentials on the surface under study. The contrast of microfields is caused by the fact that slow-moving electrons emitted from the object surface are deflected by these fields. The measurements were performed on a p-n junction to which a voltage was applied. It is shown that the type of contrast from the p-n junction can be reversed depending on the position of the contrast aperture restricting the electron beam. The same result was obtained by means of a computer simulation.
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Affiliation(s)
- S A Nepijko
- Institute of Physics, University Mainz, Staudingerweg 7, 55099 Mainz, Germany.
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42
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Nepijko SA, Sedov NN, Schönhense G. Peculiarities of imaging one- and two-dimensional structures using an electron microscope in the mirror operation mode. J Microsc 2001; 203:269-76. [PMID: 11555144 DOI: 10.1046/j.1365-2818.2001.00895.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Measurements performed in an electron microscope with the mirror operation mode are most sensitive to local electric fields and geometrical roughness of any kind of the object being studied. The object with a geometrical relief is equivalent to a smooth surface with an effective distribution of microfields. Electrons forming the image interact with the local microfields for an extended time: during approach to the object, deceleration and acceleration away from the object. As a result, the electron trajectories can be strongly distorted, and the contrast changes essentially, leading to image deformation of details of the object under investigation and to lowering of the resolution. These effects are theoretically described and are illustrated by experiments. An analysis of these effects enables the real size and the shape of the object involved to be reconstructed.
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Affiliation(s)
- S A Nepijko
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, 55099 Mainz, Germany.
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43
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Abstract
Under investigation by emission electron microscopy, the shape and size of three-dimensional objects are distorted because of the appearance of a characteristic potential relief and a possible contact potential difference between the particles and the substrate. An estimation of these effects for spherical particles is made. It is shown that the apparent size of particles observed in an emission electron microscope (EEM) could be increased as well as decreased depending on the relation between the work functions of the particle and the substrate. The corresponding formulae are given and several possibilities are shown which permit us to determine from the EEM image the real size of particles and their work function relative to the substrate.
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Affiliation(s)
- S A Nepijko
- Institute of Physics, University Mainz, Staudingerweg 7, 55099 Mainz, Germany.
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Marx GK, Elmers HJ, Schönhense G. Magneto-optical linear dichroism in threshold photoemission electron microscopy of polycrystalline Fe films. Phys Rev Lett 2000; 84:5888-5891. [PMID: 10991080 DOI: 10.1103/physrevlett.84.5888] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/1999] [Revised: 01/31/2000] [Indexed: 05/23/2023]
Abstract
Magnetic linear dichroism in threshold photoemission has been exploited to obtain magnetic contrast in a photoemission electron microscope using a mercury arc lamp. The dichroism at threshold can be described similar to the magneto-optical Kerr effect in the region of visible light. The asymmetry of electron intensity observed for a 100 nm polycrystalline Fe film on silicon is A=(0.37+/-0.05)%. The asymmetry occurs for the geometry of the transverse Kerr effect. For unpolarized light the asymmetry was about half the value observed for linearly polarized light. Threshold photoemission microscopy has a large potential for high resolution magnetic domain imaging with fast data acquisition.
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Affiliation(s)
- G K Marx
- Johannes Gutenberg-Universitat Mainz, Staudingerweg 7, D-55099 Mainz, Germany
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45
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Kuznetsov VV, Cherepkov NA, Fecher GH, Schönhense G. Angular distributions of photoelectrons ejected from fixed-in-space molecules of C3v symmetry group. J Chem Phys 1999. [DOI: 10.1063/1.478873] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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46
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Getzlaff M, Cherepkov NA, Schönhense G. Xenon on ferromagnetic surfaces: A spin-resolved photoemission study. Phys Rev B Condens Matter 1995; 52:3421-3428. [PMID: 9981461 DOI: 10.1103/physrevb.52.3421] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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47
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Westphal C, Fegel F, Bansmann J, Getzlaff M, Schönhense G, Stephens JA, McKoy V. Orientation and substrate interaction of adsorbed CO and NO molecules probed by circular dichroism in the angular distribution of photoelectrons. Phys Rev B Condens Matter 1994; 50:17534-17539. [PMID: 9976160 DOI: 10.1103/physrevb.50.17534] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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48
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Getzlaff M, Ostertag C, Fecher GH, Cherepkov NA, Schönhense G. Magnetic dichroism in photoemission with unpolarized light. Phys Rev Lett 1994; 73:3030-3033. [PMID: 10057264 DOI: 10.1103/physrevlett.73.3030] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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49
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Getzlaff M, Bansmann J, Schönhense G. Spin-resolved photoemission from physisorbed xenon on ferromagnetic surfaces: Evidence for magnetic interactions. Phys Rev Lett 1993; 71:793-796. [PMID: 10055368 DOI: 10.1103/physrevlett.71.793] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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50
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Bansmann J, Ostertag C, Schönhense G, Fegel F, Westphal C, Getzlaff M, Schäfers F, Petersen H. Circular dichroism in x-ray photoemission from core levels of nonmagnetic species. Phys Rev B Condens Matter 1992; 46:13496-13500. [PMID: 10003397 DOI: 10.1103/physrevb.46.13496] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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