Date of Award

8-7-2012

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics and Astronomy

First Advisor

Dr. Ramesh Mani

Second Advisor

Dr. Unil Perera

Third Advisor

Dr. Vadym Apalkov

Fourth Advisor

Dr. Murad Sarsour

Fifth Advisor

Dr. Douglas Gies

Abstract

This thesis consists of two parts. The first part considers the effect of microwave radiation on magnetotransport in high quality GaAs/AlGaAs heterostructure two dimensional electron systems. The effect of microwave (MW) radiation on electron temperature was studied by investigating the amplitude of the Shubnikov de Haas (SdH) oscillations in a regime where the cyclotron frequency $\omega_{c}$ and the MW angular frequency $\omega$ satisfy $2\omega \leq \omega_{c} \leq 3.5\omega$. The results indicate negligible electron heating under modest MW photoexcitation, in agreement with theoretical predictions. Next, the effect of the polarization direction of the linearly polarized MWs on the MW induced magnetoresistance oscillation amplitude was investigated. The results demonstrate the first indications of polarization dependence of MW induced magnetoresistance oscillations. In the second part, experiments on the magnetotransport of three dimensional highly oriented pyrolytic graphite (HOPG) reveal a non-zero Berry phase for HOPG. Furthermore, a novel phase relation between oscillatory magneto- and Hall- resistances was discovered from the studies of the HOPG specimen.

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