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Shokeen V, Heber M, Kutnyakhov D, Wang X, Yaroslavtsev A, Maldonado P, Berritta M, Wind N, Wenthaus L, Pressacco F, Min CH, Nissen M, Mahatha SK, Dziarzhytski S, Oppeneer PM, Rossnagel K, Elmers HJ, Schönhense G, Dürr HA. Real-time observation of non-equilibrium phonon-electron energy and angular momentum flow in laser-heated nickel. SCIENCE ADVANCES 2024; 10:eadj2407. [PMID: 38295169 PMCID: PMC10830112 DOI: 10.1126/sciadv.adj2407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 12/29/2023] [Indexed: 02/02/2024]
Abstract
Identifying the microscopic nature of non-equilibrium energy transfer mechanisms among electronic, spin, and lattice degrees of freedom is central to understanding ultrafast phenomena such as manipulating magnetism on the femtosecond timescale. Here, we use time- and angle-resolved photoemission spectroscopy to go beyond the often-used ensemble-averaged view of non-equilibrium dynamics in terms of quasiparticle temperature evolutions. We show for ferromagnetic Ni that the non-equilibrium electron and spin dynamics display pronounced variations with electron momentum, whereas the magnetic exchange interaction remains isotropic. This highlights the influence of lattice-mediated scattering processes and opens a pathway toward unraveling the still elusive microscopic mechanism of spin-lattice angular momentum transfer.
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Affiliation(s)
- Vishal Shokeen
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Michael Heber
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | | | - Xiaocui Wang
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | | | - Pablo Maldonado
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Marco Berritta
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Nils Wind
- Institut für Experimentalphysik, Universität Hamburg, 22761 Hamburg, Germany
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Lukas Wenthaus
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | | | - Chul-Hee Min
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Matz Nissen
- Institut für Experimentalphysik, Universität Hamburg, 22761 Hamburg, Germany
| | - Sanjoy K. Mahatha
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | | | - Peter M. Oppeneer
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Kai Rossnagel
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Hans-Joachim Elmers
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - Gerd Schönhense
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - Hermann A. Dürr
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
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Kink far below the Fermi level reveals new electron-magnon scattering channel in Fe. Nat Commun 2019; 10:505. [PMID: 30705281 PMCID: PMC6355843 DOI: 10.1038/s41467-019-08445-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 01/04/2019] [Indexed: 11/25/2022] Open
Abstract
Many properties of real materials can be modeled using ab initio methods within a single-particle picture. However, for an accurate theoretical treatment of excited states, it is necessary to describe electron-electron correlations including interactions with bosons: phonons, plasmons, or magnons. In this work, by comparing spin- and momentum-resolved photoemission spectroscopy measurements to many-body calculations carried out with a newly developed first-principles method, we show that a kink in the electronic band dispersion of a ferromagnetic material can occur at much deeper binding energies than expected (Eb = 1.5 eV). We demonstrate that the observed spectral signature reflects the formation of a many-body state that includes a photohole bound to a coherent superposition of renormalized spin-flip excitations. The existence of such a many-body state sheds new light on the physics of the electron-magnon interaction which is essential in fields such as spintronics and Fe-based superconductivity. The conduction electron and magnon interactions are essential for the understanding and development of spintronics and superconductivity. Here the authors show a deep binding energy kink in spin-resolved photoemission spectra which is understood as a signature the many-body spin flip excitation in Fe single crystal thin film.
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