Femtosecond photocurrents by the Dresselhaus bulk spin-galvanic effect in an inversion-asymmetric ferromagnet
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2025
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| author | Tong, Junwei Kaspar, Zdenek Alostaz, Afnan Rouzegar, Reza In, Chihun Titze, Tim Staabs, Maximilian Bierhance, Genaro Wu, Yanzhao Grisk, Holger Walowski, Jakob Münzenberg, Markus Gerhard, Felicitas Kleinlein, Johannes Kießling, Tobias Gould, Charles Molenkamp, Laurens W. Zhang, Xianmin Steil, Daniel Seifert, Tom S. Kampfrath, Tobias |
| author_facet | Tong, Junwei Kaspar, Zdenek Alostaz, Afnan Rouzegar, Reza In, Chihun Titze, Tim Staabs, Maximilian Bierhance, Genaro Wu, Yanzhao Grisk, Holger Walowski, Jakob Münzenberg, Markus Gerhard, Felicitas Kleinlein, Johannes Kießling, Tobias Gould, Charles Molenkamp, Laurens W. Zhang, Xianmin Steil, Daniel Seifert, Tom S. Kampfrath, Tobias |
| contents | We study ultrafast photocurrents in thin films of a model ferromagnetic metal with broken bulk inversion symmetry, the half-metallic Heusler compound NiMnSb, following excitation with an optical pump pulse with photon energy 1.55 eV. Remarkably, in terms of the direction of the sample magnetization M, all photocurrents are found to be a superposition of a component with Rashba- and Dresselhaus-type symmetry. We explain the Dresselhaus bulk photocurrent as follows: Pump-induced electron heating induces an excess of spin μ_s||M, which transfers spin angular momentum into states with Dresselhaus-type spin-momentum locking. The resulting charge current relaxes on a time scale of 10 fs by momentum relaxation and, thus, follows μ_s quasi-instantaneously. The relaxation of μ_s is governed by the cooling of the electrons and not by the significantly slower spin-lattice relaxation of half-metals. Our findings add the Dresselhaus spin-galvanic effect (SGE) to the set of ultrafast spin-charge-conversion phenomena. They indicate a route to more efficient spintronic terahertz emitters and detectors based on the volume scaling of the bulk SGE. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2507_00360 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Femtosecond photocurrents by the Dresselhaus bulk spin-galvanic effect in an inversion-asymmetric ferromagnet Tong, Junwei Kaspar, Zdenek Alostaz, Afnan Rouzegar, Reza In, Chihun Titze, Tim Staabs, Maximilian Bierhance, Genaro Wu, Yanzhao Grisk, Holger Walowski, Jakob Münzenberg, Markus Gerhard, Felicitas Kleinlein, Johannes Kießling, Tobias Gould, Charles Molenkamp, Laurens W. Zhang, Xianmin Steil, Daniel Seifert, Tom S. Kampfrath, Tobias Materials Science Mesoscale and Nanoscale Physics Optics We study ultrafast photocurrents in thin films of a model ferromagnetic metal with broken bulk inversion symmetry, the half-metallic Heusler compound NiMnSb, following excitation with an optical pump pulse with photon energy 1.55 eV. Remarkably, in terms of the direction of the sample magnetization M, all photocurrents are found to be a superposition of a component with Rashba- and Dresselhaus-type symmetry. We explain the Dresselhaus bulk photocurrent as follows: Pump-induced electron heating induces an excess of spin μ_s||M, which transfers spin angular momentum into states with Dresselhaus-type spin-momentum locking. The resulting charge current relaxes on a time scale of 10 fs by momentum relaxation and, thus, follows μ_s quasi-instantaneously. The relaxation of μ_s is governed by the cooling of the electrons and not by the significantly slower spin-lattice relaxation of half-metals. Our findings add the Dresselhaus spin-galvanic effect (SGE) to the set of ultrafast spin-charge-conversion phenomena. They indicate a route to more efficient spintronic terahertz emitters and detectors based on the volume scaling of the bulk SGE. |
| title | Femtosecond photocurrents by the Dresselhaus bulk spin-galvanic effect in an inversion-asymmetric ferromagnet |
| topic | Materials Science Mesoscale and Nanoscale Physics Optics |
| url | https://arxiv.org/abs/2507.00360 |