Optically controlling the competition between spin flips and intersite spin transfer in a Heusler half-metal on sub-100-fs time scales.

Ryan, Sinéad A; Johnsen, Peter C; Elhanoty, Mohamed F; Grafov, Anya; Li, Na; Delin, Anna; Markou, Anastasios; Lesne, Edouard et al. · Sci Adv · 2023

basic_science · Level V

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Abstract

The direct manipulation of spins via light may provide a path toward ultrafast energy-efficient devices. However, distinguishing the microscopic processes that can occur during ultrafast laser excitation in magnetic alloys is challenging. Here, we study the Heusler compound Co<sub>2</sub>MnGa, a material that exhibits very strong light-induced spin transfers across the entire M-edge. By combining the element specificity of extreme ultraviolet high-harmonic probes with time-dependent density functional theory, we disentangle the competition between three ultrafast light-induced processes that occur in Co<sub>2</sub>MnGa: same-site Co-Co spin transfer, intersite Co-Mn spin transfer, and ultrafast spin flips mediated by spin-orbit coupling. By measuring the dynamic magnetic asymmetry across the entire M-edges of the two magnetic sublattices involved, we uncover the relative dominance of these processes at different probe energy regions and times during the laser pulse. Our combined approach enables a comprehensive microscopic interpretation of laser-induced magnetization dynamics on time scales shorter than 100 femtoseconds.