Berlin 2024 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MA: Fachverband Magnetismus
MA 24: Terahertz Spintronics I
MA 24.11: Vortrag
Mittwoch, 20. März 2024, 12:15–12:30, EB 202
Ultrabroadband terahertz time-domain spectroscopy of giant magnetoresistance — •Zdenek Kaspar1,2, Oliver Gueckstock1, Bikash Das Mohapatra3, Tom S. Seifert1, Georg Schmidt3, and Tobias Kampfrath1 — 1Freie Universität Berlin, Germany — 2Institute of Physics of the Czech Academy of Sciences, Czech Repiblic — 3Martin-Luther-Universität Halle-Wittenberg, Germany
We perform broadband terahertz (THz) time-domain spectroscopy on giant magnetoresistance (GMR) stacks F1|Cu(3.2 nm)|F2 where F1, F2 are ferromagnetic metal thin-films with parallel (↑↑) or antiparallel (↑↓) in-plane magnetization. By utilizing ultrashort THz electric-field pulses, we measure the GMR contrast at 1-25 THz in a current-in-plane (CIP) geometry.
Our data reveal a notable decrease of the GMR contrast from 2% to 1.5% from 1 THz to 25 THz. Remarkably, we observe an almost frequency-independent time delay of 15 fs of the GMR response relative to the driving THz field. We attribute this delay to the time required for an electron to propagate through the Cu layer between F1 and F2 and to undergo spin-dependent scattering at the F1|Cu and Cu|F2 interfaces. This notion is supported by experiments, in which we increase/decrease the Cu thickness and observe an increase/decrease of the time delay.
Keywords: GMR; terahertz spectroscopy; magnetoresistance