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University of Colorado
1.
Zusin, Dmitriy.
Ultrafast Dynamics of Magnetic Multilayer Films: Magneto-Optical Spectroscopy and Resonant Scattering in the Extreme Ultraviolet and Soft X-Ray Spectral Regions.
Degree: PhD, 2018, University of Colorado
URL: https://scholar.colorado.edu/phys_gradetds/283 
► This thesis focuses on studying ferromagnetic thin films with high temporal and spatial resolution using tabletop extreme ultraviolet (EUV) light sources based on high harmonic…
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▼ This thesis focuses on studying ferromagnetic thin films with high temporal and spatial resolution using tabletop extreme ultraviolet (EUV) light sources based on high harmonic generation (HHG) and ultrafast soft X-rays from a free-electron laser. In Chapter 4, a new magneto-optical technique is developed. It allows a direct measurement of the full resonant complex EUV magneto-optical permittivity on a tabletop and thus, through a comparison with first principles calculations, is capable of capturing the microscopic mechanisms of ultrafast laser-induced demagnetization. It is found that, in Co, the demagnetization response is dominated by magnon excitations with possible smaller contributions from other mechanisms. Chapter 5 discusses the development of an efficient approach for resonant magnetic scattering (RMS) with a tabletop HHG source. This approach is used to study magnetic textures with spatial resolution. In an external magnetic field, a transition from a disordered network of stripe domains to an ordered lattice of magnetic vortices is observed in an Fe-Gd thin film. Chapter 6 presents the results of a dynamic soft X-ray RMS experiment on a disordered domain network performed at the Linear Coherent Light Source (LCLS). By directly applying the experimental data to a carefully simulated domain pattern, laser-induced transient changes in the domains are captured in real space, and strong non-uniformities in the demagnetization across the sample are observed. These non-uniformities are attributed to a combined effect of ultrafast spin-polarized currents and a gradient in the pump absorption throughout the thickness of the sample. Chapter 7 provides an outlook towards time-resolved lensless magnetic spectro-microscopy with HHG sources.
Advisors/Committee Members: Margaret M. Murnane, Henry C. Kapteyn, Thomas J. Silva.
Subjects/Keywords: extreme ultraviolet; soft x-ray; high harmonic generation; resonant magnetic scattering; magneto-optical spectroscopy; Materials Science and Engineering; Optics; Physics
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APA (6th Edition):
Zusin, D. (2018). Ultrafast Dynamics of Magnetic Multilayer Films: Magneto-Optical Spectroscopy and Resonant Scattering in the Extreme Ultraviolet and Soft X-Ray Spectral Regions. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/phys_gradetds/283
Chicago Manual of Style (16th Edition):
Zusin, Dmitriy. “Ultrafast Dynamics of Magnetic Multilayer Films: Magneto-Optical Spectroscopy and Resonant Scattering in the Extreme Ultraviolet and Soft X-Ray Spectral Regions.” 2018. Doctoral Dissertation, University of Colorado. Accessed March 09, 2021.
https://scholar.colorado.edu/phys_gradetds/283.
MLA Handbook (7th Edition):
Zusin, Dmitriy. “Ultrafast Dynamics of Magnetic Multilayer Films: Magneto-Optical Spectroscopy and Resonant Scattering in the Extreme Ultraviolet and Soft X-Ray Spectral Regions.” 2018. Web. 09 Mar 2021.
Vancouver:
Zusin D. Ultrafast Dynamics of Magnetic Multilayer Films: Magneto-Optical Spectroscopy and Resonant Scattering in the Extreme Ultraviolet and Soft X-Ray Spectral Regions. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2021 Mar 09].
Available from: https://scholar.colorado.edu/phys_gradetds/283.
Council of Science Editors:
Zusin D. Ultrafast Dynamics of Magnetic Multilayer Films: Magneto-Optical Spectroscopy and Resonant Scattering in the Extreme Ultraviolet and Soft X-Ray Spectral Regions. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/phys_gradetds/283
University of Colorado
2.
La-o-vorakiat, Chan.
Element-Selective Ultrafast Magnetization Dynamics with a Tabletop Light Source.
Degree: PhD, Physics, 2011, University of Colorado
URL: https://scholar.colorado.edu/phys_gradetds/46
► Next-generation hard-disk drives will require smaller magnetic bits and faster magnetization switching; hence, better understanding of nanoscale magnetic material is one of the key…
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▼ Next-generation hard-disk drives will require smaller magnetic bits and faster magnetization switching; hence, better understanding of nanoscale magnetic material is one of the key factors in developing of these devices. Here, I present the first ultrafast magnetization dynamics studies by use of extreme ultraviolet radiation from a tabletop high-harmonic generation source. This new probing technique offers three advantages over conventional ones: ultrafast time resolution, element selectivity, and the tabletop size.
I report three experiments showing that high harmonics are a powerful tool for probing magnetization in magnetic materials. First, our group measures simultaneously the magnetizations of Ni and Fe in Permalloy using the transverse magneto-optical Kerr effect. Second, we study laser-induced demagnetization dynamics in two ferromagnetic alloys: Permalloy and Permalloy-Cu. Contrary to a common expectation that the dynamics in strong exchange-coupled alloys would be identical, we discover that the magnetization of Fe decays earlier than that of Ni during the first 60 fs. To explain this delay, we propose a simple model incorporating a finite exchange-time factor into the magnetization rate equations. Finally, to confirm the observed sequence of dynamics in alloys, we conduct the magnetization study of elemental Fe and Ni with identical experimental conditions. The results indicate that the order of demagnetizations in the elemental forms is the same as that in Permalloy: Fe demagnetizes faster than Ni does.
Advisors/Committee Members: Henry C. Kapteyn, Margaret M. Murnane, Thomas J. Silva.
Subjects/Keywords: Demagnetization Dynamics; High-harmonic Generation; Magnetism; Ultrafast; Condensed Matter Physics
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APA (6th Edition):
La-o-vorakiat, C. (2011). Element-Selective Ultrafast Magnetization Dynamics with a Tabletop Light Source. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/phys_gradetds/46
Chicago Manual of Style (16th Edition):
La-o-vorakiat, Chan. “Element-Selective Ultrafast Magnetization Dynamics with a Tabletop Light Source.” 2011. Doctoral Dissertation, University of Colorado. Accessed March 09, 2021.
https://scholar.colorado.edu/phys_gradetds/46.
MLA Handbook (7th Edition):
La-o-vorakiat, Chan. “Element-Selective Ultrafast Magnetization Dynamics with a Tabletop Light Source.” 2011. Web. 09 Mar 2021.
Vancouver:
La-o-vorakiat C. Element-Selective Ultrafast Magnetization Dynamics with a Tabletop Light Source. [Internet] [Doctoral dissertation]. University of Colorado; 2011. [cited 2021 Mar 09].
Available from: https://scholar.colorado.edu/phys_gradetds/46.
Council of Science Editors:
La-o-vorakiat C. Element-Selective Ultrafast Magnetization Dynamics with a Tabletop Light Source. [Doctoral Dissertation]. University of Colorado; 2011. Available from: https://scholar.colorado.edu/phys_gradetds/46
University of Colorado
3.
Ruth, Maximilian Emil.
The Role of Topology in Magnetic Solitary Wave Dynamics.
Degree: MS, 2018, University of Colorado
URL: https://scholar.colorado.edu/appm_gradetds/104
► Topological solitary waves have recently attracted attention from the applied mathematics and physics communities because of both their perceived robustness and technological applications, e.g.…
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▼ Topological solitary waves have recently attracted attention from the applied mathematics and physics communities because of both their perceived robustness and technological applications, e.g. storage and logic. In the field of magnetism, topological structures include the one-dimensional domain wall and the two-dimensional magnetic skyrmion. Topology in these structures is the result of a quantized winding number, as the magnetization vector is restricted to the unit sphere. The winding number provides a notion of “topological protection”, meaning that topological wave structures cannot be continuously deformed into other structures with different winding numbers. This thesis presents two problems in magnetic solitary wave dynamics where topology plays an important role. First, transverse instabilities of elongated bound states of two precessing and translating domain walls, or bion filaments, are described. It is found that topological and non-topological domain wall pairs break into two-dimensional structures via "neck'' and "snake'' instabilities respectively. Next, the perimeter dynamics of two two-dimensional structures are described: the non-topological droplet and the topological dynamic skyrmion. A multiscale, differential geometry description is utilized to analytically obtain perimeter wave dynamics of both textures in the large-diameter limit. Energy dissipation is incorporated and an analytical expression for the textures' decay is found. Beyond this thesis, the averaged Lagrangian and differential geometry approaches have potential application in a variety of fields from optics to water waves.
Advisors/Committee Members: Mark A. Hoefer, Thomas J. Silva, Daniel Appelö.
Subjects/Keywords: averaged lagrangian; droplet; ferromagnetism; skyrmion; soliton; Applied Mathematics; Geometry and Topology
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APA (6th Edition):
Ruth, M. E. (2018). The Role of Topology in Magnetic Solitary Wave Dynamics. (Masters Thesis). University of Colorado. Retrieved from https://scholar.colorado.edu/appm_gradetds/104
Chicago Manual of Style (16th Edition):
Ruth, Maximilian Emil. “The Role of Topology in Magnetic Solitary Wave Dynamics.” 2018. Masters Thesis, University of Colorado. Accessed March 09, 2021.
https://scholar.colorado.edu/appm_gradetds/104.
MLA Handbook (7th Edition):
Ruth, Maximilian Emil. “The Role of Topology in Magnetic Solitary Wave Dynamics.” 2018. Web. 09 Mar 2021.
Vancouver:
Ruth ME. The Role of Topology in Magnetic Solitary Wave Dynamics. [Internet] [Masters thesis]. University of Colorado; 2018. [cited 2021 Mar 09].
Available from: https://scholar.colorado.edu/appm_gradetds/104.
Council of Science Editors:
Ruth ME. The Role of Topology in Magnetic Solitary Wave Dynamics. [Masters Thesis]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/appm_gradetds/104
University of Colorado
4.
Turgut, Emrah.
Studying Laser-Induced Spin Currents Using Ultrafast Extreme Ultraviolet Light.
Degree: PhD, Physics, 2014, University of Colorado
URL: https://scholar.colorado.edu/phys_gradetds/108
► Next-generation magnetic-memory devices and heat-assisted magnetic-recording applications will require a better understanding of magnetic multilayers and their interactions with optical-laser pulses. In this thesis,…
(more)
▼ Next-generation magnetic-memory devices and heat-assisted magnetic-recording applications will require a better understanding of magnetic multilayers and their interactions with optical-laser pulses. In this thesis, by combining the advantages of ultrabroad-band extreme-ultraviolet light including ultrafast time resolution, element selectivity and tabletop easy access, I report three findings in the study of ultrafast magnetization dynamics in itinerant ferromagnets. First, I experimentally prove that the transverse magneto-optical Kerr response with extreme-ultraviolet light has a purely magnetic origin and that our experimental technique is an artifact-free ultrafast magnetic probe. Second, I demonstrate the first ultrafast magnetization enhancement driven by ultrafast spin currents in Ni/Ru/Fe multilayers. Third, I engineer the sample system by choosing either insulating or spin-scattering spacer layers between the Ni and Fe magnetic layers and by structural ordering. Then, I control the competition between ultrafast spin-flip scattering and superdiffusive spin-current mechanisms; either of these processes may to be the dominant mechanism in ultrafast demagnetization.
Finally, I report two continuing experiments that are promising for future ultrafast magnetization studies with extreme-ultraviolet sources. These experiments are resonant-magnetic small-angle-scattering and the generation of bright circularly polarized high harmonics accompanied by a demonstration of the first x-ray magnetic circular dichroism with a tabletop system.
Advisors/Committee Members: Margaret M. Murnane, Henry C. Kapteyn, Daniel S. Dessau, Ivan I. Smalyukh, Thomas J. Silva.
Subjects/Keywords: Femtomagnetism; Magnetic Multilayers; Magnetization; Spintronics; Ultrafast; X-ray; Condensed Matter Physics; Optics
Record Details
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Record Details
Similar Records
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APA ·
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MLA ·
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CSE |
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Manager
APA (6th Edition):
Turgut, E. (2014). Studying Laser-Induced Spin Currents Using Ultrafast Extreme Ultraviolet Light. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/phys_gradetds/108
Chicago Manual of Style (16th Edition):
Turgut, Emrah. “Studying Laser-Induced Spin Currents Using Ultrafast Extreme Ultraviolet Light.” 2014. Doctoral Dissertation, University of Colorado. Accessed March 09, 2021.
https://scholar.colorado.edu/phys_gradetds/108.
MLA Handbook (7th Edition):
Turgut, Emrah. “Studying Laser-Induced Spin Currents Using Ultrafast Extreme Ultraviolet Light.” 2014. Web. 09 Mar 2021.
Vancouver:
Turgut E. Studying Laser-Induced Spin Currents Using Ultrafast Extreme Ultraviolet Light. [Internet] [Doctoral dissertation]. University of Colorado; 2014. [cited 2021 Mar 09].
Available from: https://scholar.colorado.edu/phys_gradetds/108.
Council of Science Editors:
Turgut E. Studying Laser-Induced Spin Currents Using Ultrafast Extreme Ultraviolet Light. [Doctoral Dissertation]. University of Colorado; 2014. Available from: https://scholar.colorado.edu/phys_gradetds/108
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