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MA: Fachverband Magnetismus
MA 48: Ultrafast Magnetization Effects II
MA 48.3: Vortrag
Freitag, 21. März 2025, 11:45–12:00, H20
Bias field studies of all-optical helicity-dependent switching. — •Kevin Jäckel1, Marcel Kohlmann1, Jakob Walowski1, Markus Münzenberg1, Yuta Sasaki2, and Karel Carva3 — 1University of Greifswald, Germany — 2Research Center for Magnetic and Spintronic Materials, Japan — 3Charles University, Czech Republic
The mechanisms underlying all-optical helicity-dependent switching AOHDS need a better understanding to improve the process towards single pulse switching. We apply external magnetic fields (anti-) parallel of up to Hext=72 mT, (opposing) supporting the desired magnetization direction in FePt granular media to disentangle the contribution of the inverse Faraday effect IFE within the switching process. Those measurements, performed on samples with varying average grain size diameters of d=10 nm, d=6 nm nm, and d=4 nm, reveal a grain size dependent impact of the applied field strength. Using the helicity-dependent refractive index calculated from density functional theory (DFT) calculations, we calculate the absorbed laser fluence for each grain size using the transfer matrix method. The absorption data, combined with the inverse Faraday constant, allows us to quantify the optically induced magnetization Δ M by the IFE. From this data, we can estimate the contribution of the IFE to the switching process. The research is funded by DFG, Fundamental aspects of all-optical pulse switching in nanometer-sized magnetic storage media Project number: 439225584.
Keywords: AOHDS; Bias field; FePt; Granular Media