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.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-3225 |
| Date | 15 May 2009 |
| Creators | Borunda Bermudez, Mario Francisco |
| Contributors | Sinova, Jairo |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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