We employ an eigenpolarization model including the description of direction dependent excitonic effects for rendering critical point structures within the dielectric function tensor of monoclinic β-Ga 2 O 3 yielding a comprehensive analysis of generalized ellipsometry data obtained from 0.75-9 eV. The eigenpolarization model permits complete description of the dielectric response. We obtain, for single-electron and excitonic band-to-band transitions, anisotropic critical point model parameters including their polarization vectors within the monoclinic lattice. We compare our experimental analysis with results from density functional theory calculations performed using the Gaussian-attenuation-Perdew-Burke-Ernzerhof hybrid density functional. We present and discuss the order of the fundamental direct band-to-band transitions and their polarization selection rules, the electron and hole effective mass parameters for the three lowest band-to-band transitions, and their excitonic contributions. We find that the effective masses for holes are highly anisotropic and correlate with the selection rules for the fundamental band-to-band transitions. The observed transitions are polarized close to the direction of the lowest hole effective mass for the valence band participating in the transition.

Vector magneto-optical generalized ellipsometry is employed for the determination of the three-dimensional magnetization properties of magnetized thin solid as well as slanted columnar thin film samples. The permalloy thin films were probed by means of Mueller matrix ellipsometry at room-temperature while an external magnetic field was rotated step-wise within each plane of a three-dimensional Cartesian coordinate system (spatial hysteresis loops). Model analysis of the magneto-optical coupling parameter (proportional to the magnetization) confirms the expected uniaxial magnetization shape of the thin solid film and reveals the three-dimensional magneto-optic anisotropy of the nanostructured thin film.

, band-to-band transitions, phonon modes, and oxidation properties of cobalt-oxide core-shell slanted columnar thin films" (2016). Faculty Publications from the Department of Electrical and Computer Engineering. 349.

We present magneto-optical dielectric function tensor data of permalloy slanted columnar thin films obtained by vector magneto-optical generalized ellipsometry. Room-temperature hysteresis magnetization measurements were performed in transverse, longitudinal, and polar configurations, and at three different sample in plane azimuth orientations. We observe strongly anisotropic hysteresis behaviors, which depend on the nanocolumn and magnetizing field orientations. We present a model dielectric function approach by implementing vectorial magneto-optical magnetization hysteresis functions with major axes coincident with the major optical polarizability axes of the nanocolumns. Our approach provides excellent match with experimental data and reveals strongly anisotropic coercive field and ferromagnetic model parameters for the permalloy slanted columnar thin films. Ferromagnetic coupling is strongest parallel to the nanocolumn direction and substantially weaker perpendicular to the nanocolumns.

No abstract