- Main
Optical spectroscopy of correlated oxides
Abstract
This dissertation presents optical studies of correlated oxide thin films mainly through the use of spectroscopic ellipsometry. The main focus is on exploring how electron- electron interactions shape the electronic properties of various transition metal oxides, although work on weakly correlated CrO₂ is also included. Epitaxial strain and temperature are employed as "tuning knobs" for material properties, often inducing and in one case completely suppressing a phase transition. A series of nickelate thin films of varying thickness and strain are investigated over broad energy and temperature ranges, spanning both the insulating and metallic phases. The far-infrared parts of the spectra are studied in the context of the extended Drude model. A detailed analysis is carried out to assess the energy scales associated with the transfer of electronic spectral weight across the insulator-to-metal transition and within the metallic state. These results are then compared to the predictions of the Mott-Hubbrad model for correlated electron systems. Additionally, a similar analysis is employed to study thin films of V₂O₃, which exhibits and insulator-to-metal transition at ̃ 150 K. Finally, a study of the ferromagnetic transition in half-metallic CrO₂ is presented. The optical response of the films along various crystallographic directions is extracted from ellipsometry data and a comparison to existing band structure calculations is presented
Main Content
Enter the password to open this PDF file:
-
-
-
-
-
-
-
-
-
-
-
-
-
-