Topics in two-dimensional systems with spin-orbit interaction

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Title: Topics in two-dimensional systems with spin-orbit interaction
Author: Borunda Bermudez, Mario Francisco
Abstract: This dissertation focuses on the study of spin -dependent transport in systems with strong spin -orbit coupling within their band structure . In particular we focus on the anomalous Hall effect , the spin Hall effect , and the Aharonov -Casher effect whose origins , are linked to the presence of spin -orbit coupling . Given the theoretical controversy surrounding these effects we further simplify our studies to semiconductor systems where the band structure is much simpler than in metallic systems with heavy elements . To obtain finite analytical results we focus on reduced dimensions (two and one dimensions ) which can be explored experimentally . To set the stage , we discuss the origins of the strong spin -orbit coupling in semiconductors deriving the effective interaction from the Dirac equation . We discuss in detail the skew scattering contribution to the anomalous Hall effect in two -dimensional systems , which is dominant for systems with low impurity concentrations , and find that it is reduced when the two chiral subbands are partially occupied in an electron gas and vanishes for a hole gas , regardless of the band filling . We also present calculations for all contributing mechanisms . We propose a device to test this prediction and study the crossover from the intrinsic to the extrinsic anomalous Hall effect . We calculate all contributions to the anomalous Hall effect in electron systems using the Kubo -Streda formalism . We find that all contributions vanish when both subbands are occupied and that the skew scattering contribution dominates when only the majority subband is occupied . We calculate the interference effects due to spin -orbit interaction in mesoscopic ring structures patterned from HgTe quantum wells related to the Aharonov -Casher effect and the spin Hall effect . We find that the transport properties are affected by the carrier density as well as the spin orbit interaction . We find that the conductivity is larger in hole gas systems . We also show that devices with inhomogenous spin orbit interaction exhibit an electrically controlled spin -flipping mechanism .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -3225
Date: 2009-05-15

Citation

Topics in two-dimensional systems with spin-orbit interaction. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -3225 .

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