Physical Sciences and Mathematics Commons^™

Finite Temperature Effects In Magnetic Materials: Model And Ab Initio Studies, Aleksander L. Wysocki

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

The understanding of finite temperature behavior of magnetic materials is of vital importance for spintronic applications. In this dissertation different theoretical techniques for studying magnetic thermodynamics of various materials are discussed. Cr₂O₃ is an antiferromagnetic insulator that was proposed to be a key component of new spintronic devices. The magnetic properties of Cr₂O₃ were studied using the LDA+U method. Magnetism was found to be very well described by the Heisenberg model. Subsequently, magnetic thermodynamics was explored using quantum pair cluster approximation. Overall, very good agreement with experiment was found for the ground state and …

Exchange Bias Training Effect In Magnetically Coupled Bilayers, Srinivas Polisetty

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

Interfaces in magnetically coupled bilayer heterostructures play a vital role in novel spintronics devices. Particularly, control of the interface spin structure enables the development of progressively down-scalable magnetic read-heads which are of major importance for non volatile magnetic recording media. Exchange bias and its accompanying training effect are fundamental magnetic coupling phenomena taking place at the interfaces of antiferromagnetic/ferromagnetic and hard/soft ferromagnetic bilayers. Here, in my thesis I present the experimental results of exchange bias training in the prototypical antiferromagnetic/ferromagnetic exchange bias system CoO/Co and the corresponding coupling and aging phenomena in the all ferromagnetic hard/soft bilayer CoPtCrB/CoCr. The latter …

Fluorescence Polarization Of Atomic, Dissociated Atomic, And Molecular Transitions Induced By Spin-Polarized Electron Impact, Jack W. Maseberg

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

Excitation of atoms by spin-polarized electron impact yields fluorescence that can generally exhibit both linear and circular polarization. For experiments where the scattered electrons are not detected, symmetry requires that the electron beam be spin polarized in order for non-zero circular polarization to be observed. Extensive theoretical and experimental investigations have been performed regarding fluorescence polarizations (Stokes parameters) resulting from spin-polarized electron impact excitation of atoms. Measurement of fluorescence polarization provides insight into the angular momentum coupling that exists in the atomic state of interest. It also enables the measurement of electron spin polarization and experimental benchmarking of theoretical atomic …

Exchange Coupling At Cobalt/ Nickel Oxide Interfaces, Andrew G. Baruth

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

Spin arrangement at interfaces in layered magnetic materials is of vital importance to the emerging field of spintronics. Knowledge of how and why the interfacial spins behave in a certain way will aid in the development of future magnetic-based memories.

Much exploration has taken place in the interlayer exchange coupling (IEC) of ferromagnetic heterostructures with in-plane anisotropy. Only recently has it become apparent that to achieve the goals of increased areal density in magnetic memory a push for exploring magnetic materials with perpendicular magnetic anisotropy (PMA) must occur. An interesting and promising candidate for such a magnetic system is [Co/Pt]/NiO/[Co/Pt], …