Physics - Condensed Matter Seminar

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Condensed Matter Seminar: "Unraveling spatial and temporal fluctuations of magnetic textures using coherent X-rays."

Event Type
Physics - Condensed Matter
190 ESB
Feb 15, 2019   1:00 pm  
Sujoy Roy, Lawrence Berkeley National Laboratory

Exotic magnetic textures that arise in magnetic thin films and nanostructures are topic of great interest. Example include recently discovered skyrmions that manifest in magnetic systems as a hexagonal lattice of spin vortices, artificial spin lattices etc. In this talk I will show that resonant coherent X-ray scattering is a powerful tool that can shed new insight into a magnetic phase. We will discuss our observation of the skyrmions using resonant soft X-ray scattering. I will discuss effect of coherent X-ray beams and optical impulses to study applied field and time dependent fluctuations of skyrmions. We obtained speckle patterns in the stripe and skyrmion phase of FeGd and determined domain cascades as a function of applied magnetic field and temperature. Using existing framework of statistical mechanics we were able to extract scaling laws for the stripe and skyrmion phase. I will also describe a new methodology that we have developed to study nanosecond correlation spectroscopy at the Linearly Coherent Light Source (LCLS). This method allows us to study spontaneous fluctuations in the sub-nanosecond time regime. Finally, I will briefly show our recent studies on generating soft X-ray orbital angular momentum beams that has the potential to unravel new information about quantum properties in materials.

Work is funded by U.S. DOE.

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