Transition of laser-induced terahertz spin currents from torque- to conduction-electron-mediated transport

Jiménez-Cavero, Pilar (Universidad de Zaragoza) ; Gueckstock, Oliver ; Nádvorník, Lukas ; Lucas, Irene (Universidad de Zaragoza) ; 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) ; Kampfrath, Tobias

Resumen: 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.

Idioma: Inglés

DOI: 10.1103/PhysRevB.105.184408

Año: 2022

Publicado en: Physical Review B 105, 18 (2022), 184408 [11 pp.]
ISSN: 2469-9950

Factor impacto JCR: 3.7 (2022)

Categ. JCR: MATERIALS SCIENCE, MULTIDISCIPLINARY rank: 157 / 343 = 0.458 (2022) - Q2 - T2
Categ. JCR: PHYSICS, CONDENSED MATTER rank: 24 / 67 = 0.358 (2022) - Q2 - T2
Categ. JCR: PHYSICS, APPLIED rank: 50 / 160 = 0.312 (2022) - Q2 - T1

Factor impacto CITESCORE: 6.7 - Physics and Astronomy (Q1) - Materials Science (Q1)

Factor impacto SCIMAGO: 1.468 - Condensed Matter Physics (Q1) - Electronic, Optical and Magnetic Materials (Q1)

Financiación: info:eu-repo/grantAgreement/EC/H2020/681917/EU/Ultrafast spin transport and magnetic order controlled by terahertz electromagnetic pulses/TERAMAG
Financiación: info:eu-repo/grantAgreement/ES/MICINN-AEI/PID2020-112914RB-I00

Tipo y forma: Article (Published version)

Área (Departamento): Área Física Materia Condensada (Dpto. Física Materia Condensa.)