A correlation spectroscopy view of spin and charge fluctuations in magnetic materials down to nanoseconds

Quantum materials are often characterized by competing order parameters that open the door to novel functionalities. Such frustrated order leads to fluctuations on multiple length and time-scales.

While slow (second) fluctuations can be detected by X-ray Photon Correlation Spectroscopy (XPCS), ultrafast (nanosecond) fluctuations are to some extent accessible to inelastic neutron scattering.

Here we propose to access the important intermediate time-scales by developing XPCS based on a novel event-based soft x-ray detector, a principle well known from high-energy physics.

We will demonstrate the new XPCS capabilities by studying spin fluctuations in topological spin textures (skyrmions), spin-ice nanostructure arrays, 2D magentic films and stripe-domains in correlated electron materials. Spin sensitivity will be achieved by tuning into soft x-ray absorption edges.

The project makes full use of the high brilliance and coherence of the new storage rings such as MAX IV, PETRA III and in the future PETRA IV. For this purpose the consortium ensembles a unique team of experts in detector technology, magnetism and XPCS. The fast XPCS capabilities to be developed in this RAC will be available to all users and benefit the whole community.