Speaker
Description
Non-colinear spin structures have gained interest due to their connection to multiferroicity. One of most well-known examples of such materials is the helical antiferromagnetic Holmium. The occurrence of domain-wall fluctuations over a wide range of time scales has been observed [1]. These fluctuations show a slow dynamic on the order of nanoseconds to seconds and are important to understand thermally-activated magnetization reversal processes. In order to probe these dynamics, techniques with nanometer spatial resolution and nanosecond temporal resolution are necessary and thus making X-ray photon correlation spectroscopy (XPCS) the ideal method. However, the temporal resolution in the soft X-ray range is often-case still limited, among others due to the detector as well the lack of coherent soft X-ray scattering beamlines in fourth-generation sources. Until now, the dynamics of Ho on the micro- to nanosecond scale has therefore not been investigated yet.
In order to increase the temporal resolution in XPCS, we have recently commissioned a mobile resonant scattering endstation at the new coherent scattering beamline SoftiMAX at the fourth-generation synchrotron source MAX IV, Sweden. Even with a slow readout CCD, this setup combined with the high coherent flux provided new intriguing insights into the dynamics of domain fluctuations: Over only a small temperature range of 10 K the dynamics change by more than two orders of magnitude. In the long-term, the goal of this instrument is to push the resolution down to the nanosecond scale and enable single-shot XPCS in the soft X-range at synchrotrons.
[1] Konings et al., Physical Review Letters 106, 7 077402 (2011).
