Probing the competition between spin-flips and spin transfer in Heusler Alloys using an Extreme Ultraviolet High Harmonic Source

Heusler alloys support a wide variety of tuneable magnetic and electronic properties as a result of their complex band structures. Such alloys can exhibit several ultrafast spin processes in response to ultrafast laser excitation. In particular, we find that intersite spin transfers, same-site spin transfers, and spin-flips all arise due to optical excitation on <100 fs timescales and manifest as rapid changes in the magneto-optical signal. We utilize a tabletop extreme ultraviolet beamline to probe the ultrafast changes in magnetization across the entire M-edges of the resonant magnetic sublattices within several Heusler alloys. By combining our energy- and time-resolved measurements with time-dependent density functional theory, we are able to disentangle the competing mechanisms that lead to ultrafast spin dynamics in Heusler materials.