Electrical & Computer Engineering, Department of
First Advisor
Mathias Schubert
Date of this Version
12-2016
Abstract
Modern growth techniques allow for highly complex nano scale thin films to be created. These new films possess highly anisotropic properties structurally, optically, and magnetically that are significantly different from that of their bulk counterparts and must be accurately characterized in order to optimize desired properties for applications in next generation devices. Current magnetometry techniques focus on high symmetry characterization, namely in and out of the sample plane, and therefore do not possess the capabilities to fully explore these anisotropic properties without complicated setups and multiple sample manipulations. The author describes a setup that combines generalized ellipsometry with an octu-pole vector magnet capable of producing magnetizing field of arbitrary amplitude and orientation to determine magneto-optical properties simultaneously in 3D without physical repositioning of samples. This combinatorial setup is referred to as vector magneto-optical generalized ellipsometry. Ferromagnetic thin films, both flat and three dimensionally structured, were probed via Mueller matrix ellipsometry at room temperature while under the influence of an external magnetic field. The resulting data was used to determine the magnetic induced changes in the dielectric tensor with model analysis and a differencing procedure. The determined changes in the dielectric tensor provide a 3D magnetic response and are used to determine magnetic anisotropy within nano-scale films both flat and highly anisotropic three dimensionally structured. The author presents and discusses results from the samples explored, both of which demonstrated shape induced magnetic anisotropy. In addition the author provides outlook for applications of the instrumentation and analysis procedure for future investigations.
Advisor: Mathias Schubert
Comments
A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Electrical Engineering, Under the Supervision of Professor Mathias Schubert. Lincoln, Nebraska: December 2016
Copyright 2016 Chad Michael Briley