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Fan T, Grychtol P, Knut R, Hernández-García C, Hickstein DD, Zusin D, Gentry C, Dollar FJ, Mancuso CA, Hogle CW, Kfir O, Legut D, Carva K, Ellis JL, Dorney KM, Chen C, Shpyrko OG, Fullerton EE, Cohen O, Oppeneer PM, Milošević DB, Becker A, Jaroń-Becker AA, Popmintchev T, Murnane MM, Kapteyn HC. Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism. Proc Natl Acad Sci U S A 2015; 112:14206-11. [PMID: 26534992 PMCID: PMC4655510 DOI: 10.1073/pnas.1519666112] [Citation(s) in RCA: 211] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.
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Affiliation(s)
- Tingting Fan
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440;
| | - Patrik Grychtol
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440
| | - Ronny Knut
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440
| | - Carlos Hernández-García
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440; Grupo de Investigación en Óptica Extrema, Universidad de Salamanca, Salamanca 37008, Spain
| | - Daniel D Hickstein
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440
| | - Dmitriy Zusin
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440
| | - Christian Gentry
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440
| | - Franklin J Dollar
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440
| | | | - Craig W Hogle
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440
| | - Ofer Kfir
- Solid State Institute and Physics Department, Technion, Haifa 32000, Israel
| | - Dominik Legut
- IT4Innovations Center, VSB Technical University of Ostrava, CZ 708 33 Ostrava, Czech Republic; Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Charles University in Prague, CZ-12116 Prague 2, Czech Republic
| | - Karel Carva
- Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Charles University in Prague, CZ-12116 Prague 2, Czech Republic; Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden
| | - Jennifer L Ellis
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440
| | - Kevin M Dorney
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440
| | - Cong Chen
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440
| | - Oleg G Shpyrko
- Department of Physics, University of California San Diego, La Jolla, CA 92093
| | - Eric E Fullerton
- Center for Magnetic Recording Research, University of California San Diego, La Jolla, CA 92093-0401
| | - Oren Cohen
- Solid State Institute and Physics Department, Technion, Haifa 32000, Israel
| | - Peter M Oppeneer
- Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden
| | - Dejan B Milošević
- Faculty of Science, University of Sarajevo, 71000 Sarajevo, Bosnia and Herzegovina; Academy of Sciences and Arts of Bosnia and Herzegovina, 71000 Sarajevo, Bosnia and Herzegovina; Max-Born-Institut, 12489 Berlin, Germany
| | - Andreas Becker
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440
| | | | - Tenio Popmintchev
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440
| | - Margaret M Murnane
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440;
| | - Henry C Kapteyn
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440
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Tesch MF, Gilbert MC, Mertins HC, Bürgler DE, Berges U, Schneider CM. X-ray magneto-optical polarization spectroscopy: an analysis from the visible region to the x-ray regime. APPLIED OPTICS 2013; 52:4294-4310. [PMID: 23842173 DOI: 10.1364/ao.52.004294] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 04/24/2013] [Indexed: 06/02/2023]
Abstract
An ultra-high vacuum compatible multipurpose chamber for magneto-optical reflection and transmission experiments with polarization analysis on magnetic systems is introduced. It is applicable in a broad photon energy range from the visible to the soft x-ray regime and for a wide angular range from grazing to normal incidence. It exploits a novel magnetization device based on rotating permanent magnets, which generates tuneable magnetic fields up to 570 mT in longitudinal, transverse and polar geometry. The unique combination of these features enables the feasibility of all typical magneto-optical spectroscopy techniques as T-MOKE, L-MOKE, P-MOKE, x-ray magneto optical linear dichroism, x-ray magnetic circular dichroism in reflection and Kerr polarization-spectroscopy, which is demonstrated for Co with focus on the Co 3p edges.
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Affiliation(s)
- M F Tesch
- University of Applied Sciences Münster, Steinfurt, Germany.
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Wietstruk M, Melnikov A, Stamm C, Kachel T, Pontius N, Sultan M, Gahl C, Weinelt M, Dürr HA, Bovensiepen U. Hot-electron-driven enhancement of spin-lattice coupling in Gd and Tb 4f ferromagnets observed by femtosecond x-ray magnetic circular dichroism. PHYSICAL REVIEW LETTERS 2011; 106:127401. [PMID: 21517350 DOI: 10.1103/physrevlett.106.127401] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Indexed: 05/30/2023]
Abstract
Femtosecond x-ray magnetic circular dichroism was used to study the time-dependent magnetic moment of 4f electrons in the ferromagnets Gd and Tb, which are known for their different spin-lattice coupling. We observe a two-step demagnetization with an ultrafast demagnetization time of 750 fs identical for both systems and slower times which differ sizeably with 40 ps for Gd and 8 ps for Tb. We conclude that spin-lattice coupling in the electronically excited state is enhanced up to 50 times compared to equilibrium.
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Affiliation(s)
- Marko Wietstruk
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, BESSY II, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
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