Karl Franzens University Graz

Graz University of Technology 

Following complex spin structures in time and space
Dr. Daniel Schick
Max-Born-Institut Berlin
16:15 - 17:15 Tuesday 17 December 2024 TUG

Controlling ultrafast spin dynamics directly on the quantum level by femtosecond light pulses promises a dramatic increase in speed, energy efficiency, and density of how we transport, process, and store information. Recent advances in the field have enabled an understanding of laser-driven spin dynamics from microscopic processes toward macroscopic functionality in magnetic nanostructures, including charge and spin transport as well as interactions with spatially extended quasiparticles such as phonons and magnons. These processes generally lead to a nanoscale spatial rearrangement of magnetization, calling for experimental techniques that can directly access the ultrafast evolution of spatially inhomogeneous spin profiles and detect the transfer or accumulation of spins at interfaces. Such observables providing nanometer spatial and femto- to picosecond temporal resolution are particularly required for investigations of complex heterostructures and non-collinear antiferromagnets, where competing interactions result in a variety of complex spin structures already in equilibrium.
In this talk, I will focus on time-resolved resonant soft-X-ray scattering (RSXS) as a unique technique for probing magnetic order in time and space with element-selectivity as well as in buried layers. RSXS combines large spectroscopic and magnetic contrast in the soft-X-ray range with access to reciprocal space in addition to nanometer depth- and lateral spatial resolution. Based on the in-house development of two laser-driven soft-X-ray sources at Max Born Institute, we have recently demonstrated the feasibility of time-resolved RSXS in laboratory experiments as a true alternative to large-scale facilities. I will discuss our recent RSXS results on the dynamics of artificial antiferromagnets, ferromagnetic domains and magnons, as well as all-optical switching in ferrimagnetic alloys.