Transport studies of interaction effects in one and two dimensional hole systems
Abstract
Interest in hole systems has increased recently due to their potential applications in 'spintronics'. They are characterized by stronger spin-orbit interaction and higher effective mass which is manifested in the form of stronger correlation effects. In this thesis, I present transport studies of hole systems grown on GaAs/AlGas heterostructures. The first project involves studies of anisotropy of spin-splitting in 1D channels by measuring conductance quantization of these channels as a function of gate voltage in the presence of an in-plane field. It is shown that the anisotropy of spin-splitting (characterized by the g-factor) in 1D channels is enhanced relative to the 2D anisotropy and is due to the crystalline anisotropy of spin-orbit interactions rather than due to lateral confinement. In the second project, I study the effect of external strain on stripe phases in quantum Hall systems. The orientation of stripes is switched as a function of strain with stripes aligning along the direction of the large external uniaxial strain applied. I also present theoretical results that were obtained as part of a collaboration initiated due to the above mentioned experiments. The theoretical work attempts to understand the origin of preferential orientation of stripes along [110] for two dimensional hole gas grown along (001) GaAs. Hartree-Fock formalism is used to estimate anisotropic exchange interaction that explains orientation of stripes for different strain values. It is also shown that internal strains present in these heterostructures could be the reason for preferential orientation of stripes along [110] in these systems.
Degree
Ph.D.
Advisors
Rokhinson, Purdue University.
Subject Area
Condensed matter physics
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