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Full-Text Articles in Physics
Optical Control Of Ultrafast Spin -Wave Relaxation By Magnetic Anisotropy In A Ferromagnet, Kevin James Smith
Optical Control Of Ultrafast Spin -Wave Relaxation By Magnetic Anisotropy In A Ferromagnet, Kevin James Smith
Dissertations, Theses, and Masters Projects
This thesis presents an investigation of the damping of spin waves in ferromagnetic Au(3 nm)/Ni(10 nm)/MgO(001) thin films using the time-resolved Magneto-optical Kerr Effect (TR-MOKE) and ferromagnetic resonance (FMR) techniques. In the optical measurements, a 150 fs, 800 nm laser beam pulse is split into pump and probe components. The pump pulse, containing most of the beam energy, thermally excites coherent spin precession. The weaker probe pulse, time-delayed by a variable beam path, captures the magnetization dynamics via the polar MOKE effect, and oscillations are observed as a function of external field amplitude and direction. The extracted precession frequency is …
Optical Characterization Of Ferromagnetic Heterostructure *Interfaces And Thin Films, Haibin Zhao
Optical Characterization Of Ferromagnetic Heterostructure *Interfaces And Thin Films, Haibin Zhao
Dissertations, Theses, and Masters Projects
This thesis presents optical characterizations of interfaces in ferromagnetic heterostructures and thin films used for spin polarized electronic devices. In these experiments, femtosecond laser spectroscopies are exploited to investigate the interface magnetization reversal, spin precession, and band offset, which are crucial in determining the performances of spintronic devices.;First, magnetization-induced second-harmonic-generation (MSHG) is applied to study interface magnetism in a hybrid structure containing a noncentrosymmetric semiconductor---Fe/AlGaAs. The reversal process of Fe interface layer magnetization is compared with the bulk magnetization reversal. In Fe/AlGaAs (001), the interface magnetization is found to be decoupled from the bulk magnetization based on the different switching …
Ultrafast Laser Spectroscopy Of Half -Metallic Chromium Dioxide, Hailong Huang
Ultrafast Laser Spectroscopy Of Half -Metallic Chromium Dioxide, Hailong Huang
Dissertations, Theses, and Masters Projects
This thesis presents ultrafast laser pump-probe differential transmission experiments on epitaxial CrO2 (110). The experiments were conducted at the wavelengths of 600 nm, 800 nm and 1200 nm, corresponding to the transition energies of 2 eV, 1.5 eV and 1 eV respectively. The wavelength dependent results, comparing with linear optical absorption, revealed the electronic structure of the material. The experimental results also showed polarization dependence of the probe beams. This is attributed to the electronic orbital anisotropy.;Temperature dependence was observed in the pump-probe experiments. The ultrafast transmission data show similar temperature dependence as ultrafast MOKE (Magneto-Optical Kerr Effect) data. A …
Thermoelastic And Photoelastic Full-Field Stress Measurement, Deonna Faye Woolard
Thermoelastic And Photoelastic Full-Field Stress Measurement, Deonna Faye Woolard
Dissertations, Theses, and Masters Projects
Photoelasticity is an optical technique that measures the difference of the principal stresses plus the principal stress direction. A complementary technique is thermoelasticity which measures the sum of the principal stresses. Combining these two full-field, non-contact nondestructive evaluation techniques allows the individual stress components to be measured. One of the main difficulties in merging these two measurement systems is in identifying an appropriate surface coating. Thermoelasticity demands a highly emissive surface, while photoelasticity requires a thick, stress-birefringent, transparent coating with a retro-reflective backing. Two coatings have been identified that can be used for combined thermoelastic and photoelastic stress measurements: PMMA …
The Projector Basis Method For Electronic Band Structure Calculations, Christopher Haas
The Projector Basis Method For Electronic Band Structure Calculations, Christopher Haas
Dissertations, Theses, and Masters Projects
Over the last several decades, two methods have emerged as the standard tools for the calculation of electronic band structures. These methods, the Car-Parinello plane wave method and the linear augmented plane wave method (LAPW), each have strengths and weaknesses in different regimes of physical problems. The Car-Parinello algorithm is ideal for calculations with soft pseudopotentials and large numbers of atoms. The LAPW method, on the other hand, easily handles all-electron and hard-core pseudopotential calculations with a small number of atoms. The projector basis method, presented here, is a hybrid mixed basis method which allows the calculation of moderately large …
Thick Target Bremsstrahlung Production, Donald I. Mcree
Thick Target Bremsstrahlung Production, Donald I. Mcree
Dissertations, Theses, and Masters Projects
No abstract provided.