Date of Award
2015
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Engineering Physics (PhD)
College, School or Department Name
Department of Physics
Advisor
Miguel Levy
Abstract
This dissertation addresses dimensionality-induced magneto-optic effects in liquid-phaseepitaxy magnetic garnet thin films. It is found that the Faraday rotation (FR) per unit length evinces a marked and steady enhancement as the film thickness is reduced below ~100 nm in Bi0.8Gd0.2Lu2Fe5O12, although it remains constant in the micron- and most of the submicron- regime. The reported specific FR change in such reduced dimensions is due to sizedependent modifications in diamagnetic transition processes in the garnet film. These processes correspond to the electronic transitions from the singlet 6S ground state to spinorbit split excited states of the Fe3+ ions in the garnet. A measurable reduction in the corresponding ferrimagnetic resonance linewidths is found, thus pointing to an increase in electronic relaxation times and longer lived excitations at reduced thicknesses than in the bulk. These changes together with a shift in vibrational frequency of the Bi-O bonds in the garnet at reduced thicknesses result in magneto-optical enhancement in ultra-thin garnet films.
This dissertation also studies optical transmittance control through multimode elliptically birefringent waveguides achieved by one-dimensional magneto-photonic crystals (MPCs) and the tuning of longitudinal magnetic bias in such waveguides, together with the tuning of the helicity of the input elliptical beam. Magnetization reversal is found to strongly reconfigure the stop band spectrum, through hybridization of the ellipticallypolarized states due to normal mode symmetry breaking.
Recommended Citation
Chakravarty, Ashim, "GEOMETRY INDUCED MAGNETO-OPTIC EFFECTS IN LPE GROWN MAGNETIC GARNET FILMS", Dissertation, Michigan Technological University, 2015.