Coherent X-ray diffraction of laser-induced magnetization dynamics and nonlinear X-ray effects
Abstract/Contents
- Abstract
- Coherent x-ray di raction is an attractive tool for studying a wide range of condensed matter systems due to the many unique advantages of x-rays - small wavelengths, large penetration depths, and chemical and elemental specifity. Soft x-rays are particularly important for the study of magnetism, as many of the important magnetic elements have strong resonances in this regime. This dissertation discusses two sets of coherent x-ray experiments. The first part focuses on the development of time-resolved optical pump x-ray probe experiments both at a synchrotron and an x-ray free electron laser (XFEL) source. Using this technique, I studied the femto- to picosecond relaxation dynamics in the labyrinth-like magnetic domains of a Co/Pd multilayer thin film following excitation by a femtosecond optical pulse. From the normalized correlation function, I isolated the elastic and fluctuating portions of the scattering intensity during the relaxation process. The emergence of XFELs such as the Linac Coherent Light Source has dramatically altered the types of experiments that are now possible, including the systematic exploration of nonlinear x-ray-matter interactions. Nonlinear spectroscopy in the optical regime has contributed immensely to our understanding of microscopic interactions and dynamical processes. The hope is to extend these spectroscopic techniques to the x-ray regime, to take advantage of the smaller wavelength, elemental and chemical specificity, and momentum resolution. One of the most promising nonlinear x-ray techniques is stimulated resonant inelastic x-ray scattering (RIXS), analogous to stimulated Raman scattering in the optical regime. The critical question is whether the threshold for stimulated RIXS will be low enough, below the sample damage threshold, for it to be a viable technique for systems of interest. In the second half of this dissertation, I demonstrate strong indications of stimulated RIXS in a high intensity single shot coherent di raction experiment at LCLS. By utilizing the strong resonant enhancements of the scattering cross-section, significant nonlinear changes in the di raction as a function of x-ray pulse intensity were detected. These observations are consistent with calculated intensities for a stimulated inelastic scattering process. Further intensity dependent spectroscopy experiments are planned for LCLS to con rm the threshold for stimulated scattering. The development of nonlinear x-ray spectroscopic techniques will certainly revolutionize existing fields as well as spawn entirely new fields of research.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2012 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Wu, Benny Cheng Han |
|---|---|
| Associated with | Stanford University, Department of Applied Physics |
| Primary advisor | Fisher, Ian R. (Ian Randal) |
| Primary advisor | Stöhr, Joachim |
| Thesis advisor | Fisher, Ian R. (Ian Randal) |
| Thesis advisor | Stöhr, Joachim |
| Thesis advisor | Lindenberg, Aaron Michael |
| Advisor | Lindenberg, Aaron Michael |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Benny Wu. |
|---|---|
| Note | Submitted to the Department of Applied Physics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2012. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2012 by Benny Cheng Han Wu
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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