Regensburg 2025 – scientific programme
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MA: Fachverband Magnetismus
MA 48: Ultrafast Magnetization Effects II
MA 48.5: Talk
Friday, March 21, 2025, 12:15–12:30, H20
Indications of terahertz spin transport in the altermagnet candidate RuO2 — •Oliver Gueckstock1, Clara Simons1, Maik Gaerner2, Zdenek Kaspar3, Jiri Jechumtal3, Tom S. Seifert1, Lukas Nadvornik3, Günter Reiss2, and Tobias Kampfrath1 — 1FU Berlin — 2U Bielefeld — 3Charles University Prague
The recently emerging material class of altermagnets has large potential to offer properties like strong spin splitting, which are so far rather typical for classical ferromagnets [1]. RuO2 appears to be a promising metallic altermagnet candidate with huge spin splitting in the electronic band structure and for photoinduced spin and orbital transport with a Néel temperature above room temperature [1,2]. Here, we apply femtosecond laser pulses to RuO2(110)|HM stacks consisting of a twinned RuO2 layer and a heavy-metal layer HM of Pt or W. We observe THz emission signals with distinct pump-polarization dependence. The signals change sign when HM=Pt is replaced by W and exhibit a marked temperature dependence, thereby suggesting a magnetism-related signal origin. We discuss possible mechanisms of THz-signal generation, including an ultrafast photoinduced spin current from RuO2 to HM and its conversion into in-plane charge in HM, which gives rise to the emission of a THz electromagnetic pulse. References: [1] Smejkal et al., Phys Rev. X 12, 040501 (2022), [2] Adamantopoulos et al., npj spintronics 2, 46 (2024)
Keywords: terahertz emission; altermagnets; ultrafast spin transport