On ferromagnetic thin films and two-dimensional magneto-optic photonic crystals
This thesis presents results in two different neighboring areas of research: the magnetic properties of thin ferrite films and the application of the films in two-dimensional photonic crystals. In the first part, we investigate the accuracy of the customary method for determining the magnetic anisotropy constants of ferrite films by ferromagnetic resonance (FMR) experiment. We have improved the method and introduced an experimental procedure to obtain the anisotropy constants with higher precision. The magnetic anisotropy fields are obtained by using FMR on a (111)-oriented yttrium iron garnet (YIG) film made by pulsed laser deposition. Moreover, we found experimentally that the shapes of FMR spectra of laser deposited epitaxial YIG films strongly depend on the orientation of the magnetic bias field with respect to the crystalline axes of the film. Inhomogeneities of the constants of anisotropy throughout the film could be responsible for the complexity of the FMR spectra. We find the special directions of the applied magnetic field in which the contribution of the magnetocrystalline anisotropy has the smallest effect on the ferromagnetic resonance and therefore on the elements of the permeability tensor. In the second part, we study the electromagnetic wave propagation in two-dimensional (2D) dielectric and magneto-optic photonic crystals (PCs). We have proposed a 2D PC which is composed of magneto-optic material for the purpose of the enhancement of Faraday rotation in high transmission. It is assumed that the 2D PC contains a bismuth iron garnet (BIG) film either as the PC background medium or as a defect, embedded in the 2D PC. We have examined theoretically and computationally the increase in the Faraday rotation as well as the transmission of a plane-polarized plane wave incident onto these structures in the optical wavelength regime. Several important phenomena, with potential applications, are observed.
School:Kungliga Tekniska högskolan
Source Type:Doctoral Dissertation
Keywords:NATURAL SCIENCES; Physics; Physics; photonic crystals; physics; Fysik
Date of Publication:01/01/2004