Dr. Peter Fischer, IEEE Fellow, Lawrence Berkeley National Laboratory, USA
Biography: Dr. Peter Fischer received his PhD in Physics (Dr.rer.nat.) from the Technical University in Munich, Germany in 1993 on pioneering work with X-ray magnetic circular dichroism in rare earth systems and his Habilitation from the University in Würzburg, Germany in 2000 based on his pioneering work on Magnetic Soft X-ray microscopy. Since 2004 he is with the Materials Sciences Division at Lawrence Berkeley National Laboratory in Berkeley CA. He is Senior Staff Scientist and Principal Investigator in the Non-Equilibrium Magnetic Materials Program and currently also Deputy Division Director at MSD. His research program is focused on the use of polarized synchrotron radiation for the study of fundamental problems in magnetism. Since 2014 he is also Adjunct Professor for Physics at the University of California in Santa Cruz. Dr. Fischer has published more than 200 peer reviewed papers and has given about 300 invited presentations at national and international conferences. He was nominated as Distinguished Lecturer of the IEEE Magnetics Society in 2011. For his achievements of “hitting the 10nm resolution milestone with soft X-ray microscopy” he received the Klaus Halbach Award at the Advanced Light Source in 2010. Dr. Fischer is Fellow of the APS and IEEE.

Speech Title: X-raying non-trivial spin textures – recent achievements and future opportunities
Abstract: Spin textures and their dynamics hold the key to understand and control the properties, behavior and functionalities of novel magnetic materials, which can impact the speed, size and energy efficiency of spin driven technologies. Advanced characterization tools that provide magnetic sensitivity to spin textures at high spatial resolution, ultimately at buried interfaces and in all three dimensions [1], and at high temporal resolution to capture the spin dynamics across scales, are therefore of large scientific interest.
Magnetic soft X-ray spectro-microscopies [2] provide unique characterization opportunities to study the statics and dynamics of spin textures in magnetic materials combining X-ray magnetic circular dichroism (X-MCD) as element specific, quantifiable magnetic contrast mechanism with spatial and temporal resolutions down to fundamental magnetic length, time, and energy scales.
Current developments of x-ray sources aim to increase dramatically the coherence of x-rays opening the path to new techniques, such as ptychography [3] or x-ray photo-correlation spectroscopy (XPCS) [4] that allow unprecedented studies of nanoscale heterogeneity, complexity, and fluctuations.
I will review recent achievements and future opportunities with magnetic x-ray spectro-microscopies. Examples will include the static properties and dynamic behavior of magnetic skyrmions [5,6] textures with potential application to novel magnetic logic and storage devices, as well as results from an XPCS study at LCLS with a novel 2-pulse scheme that allowed to discover an unexpected and drastic change of the correlation times in nanoscale spin fluctuations near phase boundaries, i.e., in the skyrmion phase, and near the boundary with the stripe phase of a multilayered Fe/Gd system [4].

Acknowledgement: This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division Contract No. DE-AC02-05-CH1123 in the Non-Equilibrium Magnetic Materials Program (MSMAG).

References: [1] A. Fernandez-Pacheco, et al., Nature Comm 8 15756 (2017)
[2] P. Fischer and H. Ohldag, Report on Progress in Physics 78 094501 (2015)
[3] X. Shi, et al, Appl Phys Letter 108, 094103 (2016)
[4] M. H. Seaberg, et al, Phys Rev Lett 119 067403 (2017)
[5] S. Woo, et al., Nature Materials 15 501 (2016)
[6] S. Woo, et al., Nature Comm 8:15573 (2017)

Keywords: X-ray magnetic circular dichroism, magnetic x-ray spectromicroscopy, spin dynamics, chiral spin textures.