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

TL;DR

This study investigates ultrafast laser-induced spin dynamics in the Heusler compound Co2MnGa, revealing the competition between spin transfer and spin-flip processes on sub-100 femtosecond timescales using advanced spectroscopy and theoretical modeling.

Contribution

It provides a detailed microscopic understanding of competing ultrafast spin processes in a Heusler alloy, combining element-specific measurements with time-dependent density functional theory.

Findings

Identified dominance of specific spin transfer processes at different energies and times.

Demonstrated the ability to disentangle multiple ultrafast spin phenomena.

Uncovered the role of spin-orbit mediated spin-flips in ultrafast magnetization dynamics.

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 Co2MnGa, 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 Co2MnGa: 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 timescales shorter than 100 fs.