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Effects of asymmetry on electron spin dynamics in gallium arsenide quantum wells

Effects of asymmetry on electron spin dynamics in gallium arsenide quantum wells
Effects of asymmetry on electron spin dynamics in gallium arsenide quantum wells
This work presents optical studies of electron spin dynamics in gallium arsenide (GaAs) quantum wells, focusing on the effect of inversion asymmetric confinement potentials on spin lifetimes in quantum wells grown on (110)-oriented substrates. Inversion asymmetry in the presence of the spin orbit interaction offers the possibility of complete control of electron spin dynamics in GaAs quantum wells. Symmetry arguments predict any inversion asymmetric two dimensional potential will reduce spin lifetimes via the Dyakonov-Perel spin relaxation mechanism. One aim of this work has been to make a comparison of the effect produced by an electric field to that from alloy engineering.
The suppression of the Dyakonov-Perel spin relaxation mechanism in (110) quantum wells makes them ideal candidates for measuring increases in spin relaxation due to asymmetry. To measure temporal spin dynamics, the time-resolved Kerr rotation technique was adapted in order to compensate for reduced rotational symmetry in the (110) crystallographic direction. An investigation into the effect of a transverse electric field on electron spin lifetimes was conducted. By combining spin lifetime with electron scattering time measurements it was possible to provide the first direct measurement of the Rashba coefficient. There is good agreement with k.p theory at low temperatures; however there is an unexplained increase with temperature.
Spin dynamics measurements were carried out on quantum wells with asymmetric alloy composition. Through the combination of electron spin lifetime and electron scattering time measurements it was shown that the effect of alloy engineering on electron spin dynamics is very small. This is consistent with theoretical predictions and highlights the importance of considering both conduction and valence band potentials for the understanding of the effect of asymmetry on electron spin dynamics in quantum wells.
Eldridge, Peter Stephen
609b0f9d-6a9b-4ed4-9e83-75427dc15960
Eldridge, Peter Stephen
609b0f9d-6a9b-4ed4-9e83-75427dc15960
Harley, Richard
54613031-f60f-45f4-9b20-e49bcfd53b77

Eldridge, Peter Stephen (2009) Effects of asymmetry on electron spin dynamics in gallium arsenide quantum wells. University of Southampton, School of Physics and Astronomy, Doctoral Thesis, 118pp.

Record type: Thesis (Doctoral)

Abstract

This work presents optical studies of electron spin dynamics in gallium arsenide (GaAs) quantum wells, focusing on the effect of inversion asymmetric confinement potentials on spin lifetimes in quantum wells grown on (110)-oriented substrates. Inversion asymmetry in the presence of the spin orbit interaction offers the possibility of complete control of electron spin dynamics in GaAs quantum wells. Symmetry arguments predict any inversion asymmetric two dimensional potential will reduce spin lifetimes via the Dyakonov-Perel spin relaxation mechanism. One aim of this work has been to make a comparison of the effect produced by an electric field to that from alloy engineering.
The suppression of the Dyakonov-Perel spin relaxation mechanism in (110) quantum wells makes them ideal candidates for measuring increases in spin relaxation due to asymmetry. To measure temporal spin dynamics, the time-resolved Kerr rotation technique was adapted in order to compensate for reduced rotational symmetry in the (110) crystallographic direction. An investigation into the effect of a transverse electric field on electron spin lifetimes was conducted. By combining spin lifetime with electron scattering time measurements it was possible to provide the first direct measurement of the Rashba coefficient. There is good agreement with k.p theory at low temperatures; however there is an unexplained increase with temperature.
Spin dynamics measurements were carried out on quantum wells with asymmetric alloy composition. Through the combination of electron spin lifetime and electron scattering time measurements it was shown that the effect of alloy engineering on electron spin dynamics is very small. This is consistent with theoretical predictions and highlights the importance of considering both conduction and valence band potentials for the understanding of the effect of asymmetry on electron spin dynamics in quantum wells.

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Published date: May 2009
Organisations: University of Southampton

Identifiers

Local EPrints ID: 69729
URI: http://eprints.soton.ac.uk/id/eprint/69729
PURE UUID: 9911e4cb-4756-4ba1-ba9d-2663ea2d411e

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Date deposited: 27 Nov 2009
Last modified: 08 Jan 2022 23:46

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Contributors

Author: Peter Stephen Eldridge
Thesis advisor: Richard Harley

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