Persistent Link:
http://hdl.handle.net/10150/311342
Title:
Magnetization Dynamics at Elevated Temperatures
Author:
Xu, Lei
Issue Date:
2013
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The area of ultrafast (sub-nanosecond) magnetization dynamics of ferromagnetic elements and thin films, usually driven by a strong femtosecond laser pulse, has experienced intense research interest. In this dissertation, laser-induced demagnetization is theoretically studied by taking into account interactions among electrons, spins, and lattice. We propose a microscopic approach under the three temperature framework and derive the equations that govern the demagnetization at arbitrary temperatures.To address the question of magnetization reversal at high temperatures, the conventional Landau-Lifshitz equation is obviously unsatisfactory, since it fails to describe the longitudinal relaxation. So by using the equation of motion for the quantum density matrix within the instantaneous local relaxation time approximation, we propose an effective equation that is capable of addressing magnetization dynamics for a wide range of temperatures. The longitudinal and transverse relaxations are analyzed, magnetization reversal processes near Curie temperatures is also studied. Furthermore, we compared our derived Self-consistent Bloch equation and Landau-Lifshitz-Bloch equation in detail. Finally, the demagnetzation dynamics for ferromagnetic and ferrimagnetic alloys is studied by solving the Self-consistent Bloch equation.
Type:
text; Electronic Dissertation
Keywords:
heat assisted magnetic recording; high temperature; longitudinal relaxation; magnetization dynamics; Self-consistent Bloch equation; Physics; demagnetization
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Physics
Degree Grantor:
University of Arizona
Advisor:
Zhang, Shufeng

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleMagnetization Dynamics at Elevated Temperaturesen_US
dc.creatorXu, Leien_US
dc.contributor.authorXu, Leien_US
dc.date.issued2013-
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe area of ultrafast (sub-nanosecond) magnetization dynamics of ferromagnetic elements and thin films, usually driven by a strong femtosecond laser pulse, has experienced intense research interest. In this dissertation, laser-induced demagnetization is theoretically studied by taking into account interactions among electrons, spins, and lattice. We propose a microscopic approach under the three temperature framework and derive the equations that govern the demagnetization at arbitrary temperatures.To address the question of magnetization reversal at high temperatures, the conventional Landau-Lifshitz equation is obviously unsatisfactory, since it fails to describe the longitudinal relaxation. So by using the equation of motion for the quantum density matrix within the instantaneous local relaxation time approximation, we propose an effective equation that is capable of addressing magnetization dynamics for a wide range of temperatures. The longitudinal and transverse relaxations are analyzed, magnetization reversal processes near Curie temperatures is also studied. Furthermore, we compared our derived Self-consistent Bloch equation and Landau-Lifshitz-Bloch equation in detail. Finally, the demagnetzation dynamics for ferromagnetic and ferrimagnetic alloys is studied by solving the Self-consistent Bloch equation.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectheat assisted magnetic recordingen_US
dc.subjecthigh temperatureen_US
dc.subjectlongitudinal relaxationen_US
dc.subjectmagnetization dynamicsen_US
dc.subjectSelf-consistent Bloch equationen_US
dc.subjectPhysicsen_US
dc.subjectdemagnetizationen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePhysicsen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorZhang, Shufengen_US
dc.contributor.committeememberFleming, Seanen_US
dc.contributor.committeememberLeroy, Brianen_US
dc.contributor.committeememberSandhu, Arvinderen_US
dc.contributor.committeememberJacquod, Philippeen_US
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