149142 20251017144633.0 doi 10.1103/PhysRevB.105.184408 sideral 129147 ART-2022-129147 eng Jiménez-Cavero, Pilar Universidad de Zaragoza (orcid)0000-0003-0400-8600 Transition of laser-induced terahertz spin currents from torque- to conduction-electron-mediated transport 2022 Access copy available to the general public Unrestricted Spin transport is crucial for future spintronic devices operating at bandwidths up to the terahertz range. In F|N thin-film stacks made of a ferromagnetic/ferrimagnetic layer F and a normal-metal layer N, spin transport is mediated by (1) spin-polarized conduction electrons and/or (2) torque between electron spins. To identify a crossover from (1) to (2), we study laser-driven spin currents in F|Pt stacks where F consists of model materials with different degrees of electrical conductivity. For the magnetic insulators yttrium iron garnet, gadolinium iron garnet (GIG) and ¿-Fe2O3, identical dynamics is observed. It arises from the terahertz interfacial spin Seebeck effect (SSE), is fully determined by the relaxation of the electrons in the metal layer, and provides a rough estimate of the spin-mixing conductance of the GIG/Pt and ¿-Fe2O3/Pt interfaces. Remarkably, in the half-metallic ferrimagnet Fe3O4 (magnetite), our measurements reveal two spin-current components with opposite direction. The slower, positive component exhibits SSE dynamics and is assigned to torque-type magnon excitation of the A- and B-spin sublattices of Fe3O4. The faster, negative component arises from the pyrospintronic effect and can consistently be assigned to ultrafast demagnetization of minority-spin hopping electrons. This observation supports the magneto-electronic model of Fe3O4. In general, our results provide a route to the contact-free separation of torque- and conduction-electron-mediated spin currents. © 2022 authors. Published by the American Physical Society. info:eu-repo/grantAgreement/EC/H2020/681917/EU/Ultrafast spin transport and magnetic order controlled by terahertz electromagnetic pulses/TERAMAG This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 681917-TERAMAG info:eu-repo/grantAgreement/ES/MICINN-AEI/PID2020-112914RB-I00 info:eu-repo/semantics/openAccess by https://creativecommons.org/licenses/by/4.0/deed.es 3.7 2022 MATERIALS SCIENCE, MULTIDISCIPLINARY 157 / 343 = 0.458 2022 Q2 T2 PHYSICS, CONDENSED MATTER 24 / 67 = 0.358 2022 Q2 T2 PHYSICS, APPLIED 50 / 160 = 0.312 2022 Q2 T1 1.468 2022 Electronic, Optical and Magnetic Materials 2022 Q1 Condensed Matter Physics 2022 Q1 6.7 2022 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Gueckstock, Oliver Nádvorník, Lukas Lucas, Irene Universidad de Zaragoza (orcid)0000-0003-0271-8713 Seifert, Tom S. Wolf, Martin Rouzegar, Reza Brouwer, Piet W. Becker, Sven Jakob, Gerhard Kläui, Mathias Guo, Chenyang Wan, Caihua Han, Xiufeng Jin, Zuanming Zhao, Hui Wu, Di Morellón, Luis Universidad de Zaragoza (orcid)0000-0003-3724-508X Kampfrath, Tobias 2003 395 Universidad de Zaragoza Dpto. Física Materia Condensa. Área Física Materia Condensada 105, 18 (2022), 184408 [11 pp.] Phys. Rev. B Physical Review B 2469-9950 915871 http://zaguan.unizar.es/record/149142/files/texto_completo.pdf Versión publicada 2724736 http://zaguan.unizar.es/record/149142/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:149142 articulos driver 2025-10-17-14:27:32 ARTICLE