One of the most significant impediments to understand ultrafast spin-manipulation is that the experimentalists’ tools of choice – time-resolved magneto-optical Kerr effect (MOKE), magnetic circular dichroism (MCD), and angle-resolved photoemission spectroscopy (ARPES) - remain beyond the reach of ab-initio simulations for solids. A direct comparison between theory and experiment, the bedrock of progress in other branches of solid state physics, is therefore absent in the field of ultrafast spin manipulation. This project aims to rectify this by (i) developing an ab-initio theory of these experimental techniques, i.e., a theory of time-resolved MOKE, MCD, as well as a working theory for time-resolved (AR)PES and (ii) implementing this theory in a state-of-the-art time-dependent density functional theory (TDDFT) code. With these tools in hand the project then aims, in close collaboration with experiments, to (iii) elucidate the underlying physical mechanisms behind the ultrafast dynamics of spin and charge and, (iv), study and design new materials such as ferromagnetic/anti-ferromagnetic (FM/AFM), anti-ferromagnetic/non-magnetic (AFM/NM) and FM/NM interfaces with a view to control spin by light.
Substrate-controlled ultrafast spin injection and demagnetization
J. K. Dewhurst, S. Shallcross, E. K. U. Gross, and S. Sharma
Phys. Rev. Applied 10, 044065 (2018) - DOI: 10.1103/PhysRevApplied.10.0440