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MA: Fachverband Magnetismus

MA 24: Terahertz Spintronics I

MA 24.14: Vortrag

Mittwoch, 20. März 2024, 13:00–13:15, EB 202

Magnon terahertz spin transport in metallic Gd|Pt thin-films — •Oliver Gueckstock^1,2, Tim Amrhein¹, Tom S. Seifert¹, Martin Weinelt¹, Tobias Kampfrath^1,2, and Nele Thielemann-Kühn¹ — ¹FU Berlin, Berlin, Germany — ²FHI Berlin, Berlin, Germany

Transport of spin angular momentum is a fundamental operation required for future spin-electronic devices. To be competitive with other information carriers, it is required to push spin transport to ultrafast time scales [1]. Here, we use femtosecond laser pulses to trigger ultrafast spin transport in prototypical F|N bilayers from a ferromagnetic layer F into a nonmagnetic metal layer N [2]. Following absorption of the pump, a spin current in F is launched and converted into a transverse charge current in N, where it gives rise to the emission of a THz electromagnetic pulse [2]. Two driving forces can occur: (i) a temperature gradient (Seebeck-like effect) [3] and (ii) a spin-voltage gradient [4]. In metallic F, (ii) dominates and relies on conduction electrons, while (i) is found for insulating F [3,4]. Remarkably, in the fully metallic ferromagnet Gd, we find Seebeck-type dynamics and, thus, spin transport due to magnons. This finding highlights the great importance of magnon-mediated spin transport, in particular in metallic systems. References: [1] Vedmedenko et al., J. Phys. D: Appl. Phys. 53, 453001 (2020), [2] T. Seifert et al., Nat. Phot. 10, 483 (2016), [3] T. Seifert et al., Nat. Comm. 9, 2899 (2018), [4] R. Rouzegar et al., Phys. Rev. B 105, 184408 (2022).

Keywords: terahertz spectroscopy; ultrafast magnetism; spin transport; spintronics; gadolinium