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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. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 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] [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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2
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Zhao YC, Lyu HC, Yang G, Dong BW, Qi J, Zhang JY, Zhu ZZ, Sun Y, Yu GH, Jiang Y, Wei HX, Wang J, Lu J, Wang ZH, Cai JW, Shen BG, Zhan WS, Yang F, Zhang SJ, Wang SG. Direct observation of magnetic contrast obtained by photoemission electron microscopy with deep ultra-violet laser excitation. Ultramicroscopy 2019; 202:156-162. [PMID: 31063898 DOI: 10.1016/j.ultramic.2019.04.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 03/31/2019] [Accepted: 04/17/2019] [Indexed: 11/28/2022]
Abstract
Magnetic circular dichroism (MCD) and magnetic linear dichroism (MLD) have been investigated in a photoemission electron microscopy (PEEM) system excited by a deep ultra-violet (DUV) laser (with λ = 177.3 nm and hυ = 7.0 eV) for the first time. High resolution PEEM magnetic images (down to 43.2 nm) were directly obtained on a (001)-oriented magnetic FePt film surface with a circularly-polarized light under normal incidence. Furthermore, a stepped Cr seeding layer was applied to induce the formation of large-area epitaxial FePt films with (001) and (111) two orientations, where MLD with large asymmetry was observed in the transition area of two phases. It demonstrates that DUV laser can be a powerful source for high resolution magnetic imaging in the laboratory in absence of synchrotron facilities.
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Affiliation(s)
- Y C Zhao
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - H C Lyu
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - G Yang
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - B W Dong
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - J Qi
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - J Y Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Z Z Zhu
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Y Sun
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - G H Yu
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Y Jiang
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - H X Wei
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - J Wang
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - J Lu
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Z H Wang
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - J W Cai
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - B G Shen
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - W S Zhan
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - F Yang
- Key Lab of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - S J Zhang
- Key Lab of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - S G Wang
- State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
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3
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Chiang CT, Winkelmann A, Yu P, Kirschner J. Magnetic dichroism from optically excited quantum well states. PHYSICAL REVIEW LETTERS 2009; 103:077601. [PMID: 19792686 DOI: 10.1103/physrevlett.103.077601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Indexed: 05/28/2023]
Abstract
We demonstrate magnetic dichroism from optically excited states in two-photon photoemission. Using ultrathin cobalt films grown on Cu(001), we observe unoccupied quantum well states which give rise to a sizable intensity change in photoemission under magnetization reversal. The simultaneous comparison of both circular and linear magnetic dichroism in the same system permits us to check fundamental symmetry requirements and allows us to explicitly elucidate the common origin of both effects. Based on our observations we argue that the observed effect is related to spin-orbit coupling in the intermediate quantum well states.
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Affiliation(s)
- Cheng-Tien Chiang
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle(Saale), Germany
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Nakagawa T, Watanabe K, Matsumoto Y, Yokoyama T. Magnetic circular dichroism photoemission electron microscopy using laser and threshold photoemission. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:314010. [PMID: 21828571 DOI: 10.1088/0953-8984/21/31/314010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We demonstrate that laser induced valence band photoemission can be used in the observation of magnetic domain structures with a magnetic circular dichroism photoemission electron microscope (MCD-PEEM). It has been widely considered that valence band photoemission MCD asymmetry is rather small compared to that obtained with x-rays because of its weak spin-orbit coupling. However, we show that the MCD asymmetry is high near the photoemission threshold, permitting us to perform MCD-PEEM experiments. The use of intense and pulsed lasers as excitation sources enables PEEM studies of two-photon photoemission MCD and all optical time resolved MCD.
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Affiliation(s)
- Takeshi Nakagawa
- Institute for Molecular Science, Myodaiji-cho, Okazaki, Aichi 444-8585, Japan
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5
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Hild K, Maul J, Schönhense G, Elmers HJ, Amft M, Oppeneer PM. Magnetic circular dichroism in two-photon photoemission. PHYSICAL REVIEW LETTERS 2009; 102:057207. [PMID: 19257547 DOI: 10.1103/physrevlett.102.057207] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [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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7
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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. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 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] [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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Nakagawa T, Yokoyama T, Hosaka M, Katoh M. Measurements of threshold photoemission magnetic dichroism using ultraviolet lasers and a photoelastic modulator. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2007; 78:023907. [PMID: 17578123 DOI: 10.1063/1.2437165] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
A magneto-optical method based on valence band photoemission by laser excitation is described. Total photoexcited electron dichroism is detected using wave plates or a photoelastic modulator. Compared to the direct current method using wave plates, a modulation technique assisted by a photoelastic modulator has an advantage to improve the signal-to-noise ratio of magnetic dichroism by a factor of 10. The magnetic circular and linear dichroism can be investigated with this technique. An application to magnetic domain imaging using photoemission electron microscope is also demonstrated.
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Affiliation(s)
- Takeshi Nakagawa
- Department of Molecular Structure, Institute for Molecular Science, Myodaiji-cho, Okazaki 444-8585, Japan.
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Nakagawa T, Yokoyama T. Magnetic circular dichroism near the Fermi level. PHYSICAL REVIEW LETTERS 2006; 96:237402. [PMID: 16803401 DOI: 10.1103/physrevlett.96.237402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2006] [Indexed: 05/10/2023]
Abstract
We report the observation of enhanced magnetic circular dichroism (MCD) near the Fermi level using visible and ultraviolet lasers. More than 10% MCD asymmetry is achieved for a perpendicularly magnetized 12 ML (monolayer) Ni film on Cu(001). By changing the work function with the aid of cesium adsorption, the MCD asymmetry of is found to be enhanced only near the photoemission threshold and to drop down to 0.1% at the photon energy larger than the work function by 0.6 eV. A theoretical calculation also shows enhanced MCD near the photoemission threshold, qualitatively in agreement with the experimental results. Other ultrathin films of 6 ML Ni, 15 ML Co, and 3 and 15 ML Fe on Cu(001) are also investigated. It is found that the perpendicularly magnetized films show much larger MCD asymmetries than the in-plane magnetized films as in the Kerr effect.
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Affiliation(s)
- Takeshi Nakagawa
- Department of Molecular Structure, Institute for Molecular Science, and Department of Structural Molecular Science, The Graduate University for Advanced Studies (Sokendai), Myodaiji-cho, Okazaki, 444-8585, Japan
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