Phase coherence in graphene
The phase coherent properties of electrons in low temperature graphene are measured and analyzed. I demonstrate that graphene is able to coherently transport spin-polarized electrons over micrometer distances, and prove that magnetic defects in the graphene sheet are responsible for limiting spin tr...
Main Author: | |
---|---|
Language: | English |
Published: |
University of British Columbia
2013
|
Online Access: | http://hdl.handle.net/2429/45614 |
id |
ndltd-UBC-oai-circle.library.ubc.ca-2429-45614 |
---|---|
record_format |
oai_dc |
spelling |
ndltd-UBC-oai-circle.library.ubc.ca-2429-456142018-01-05T17:27:04Z Phase coherence in graphene Lundeberg, Mark Brian The phase coherent properties of electrons in low temperature graphene are measured and analyzed. I demonstrate that graphene is able to coherently transport spin-polarized electrons over micrometer distances, and prove that magnetic defects in the graphene sheet are responsible for limiting spin transport over longer distances. It is shown that these magnetic defects are also partly responsible for the high decoherence (phase loss) observed at low temperature, and that another (as yet unknown) non-magnetic mechanism is required to explain the remainder. Similar measurements are used to probe and characterize the size scales of the roughness of the graphene sheet. The effects of an in-plane magnetic field threading through the rough graphene sheet are analogous to the effects of the built-in strain; I argue that the observed large valley-dependent scattering rates are a consequence of this built-in strain. I also describe an original, robust technique for extracting coherence information from conductance fluctuations. The technique is demonstrated in experiments on graphene, used to efficiently detect the presence of magnetic defects. This new approach to studying phase coherence can be easily carried over to other mesoscopic semiconducting systems. Science, Faculty of Physics and Astronomy, Department of Graduate 2013-12-12T15:32:14Z 2013-12-12T15:32:14Z 2013 2014-05 Text Thesis/Dissertation http://hdl.handle.net/2429/45614 eng Attribution-ShareAlike 2.5 Canada http://creativecommons.org/licenses/by-sa/2.5/ca/ University of British Columbia |
collection |
NDLTD |
language |
English |
sources |
NDLTD |
description |
The phase coherent properties of electrons in low temperature graphene are measured and analyzed. I demonstrate that graphene is able to coherently transport spin-polarized electrons over micrometer distances, and prove that magnetic defects in the graphene sheet are responsible for limiting spin transport over longer distances. It is shown that these magnetic defects are also partly responsible for the high decoherence (phase loss) observed at low temperature, and that another (as yet unknown) non-magnetic mechanism is required to explain the remainder.
Similar measurements are used to probe and characterize the size scales of the roughness of the graphene sheet. The effects of an in-plane magnetic field threading through the rough graphene sheet are analogous to the effects of the built-in strain; I argue that the observed large valley-dependent scattering rates are a consequence of this built-in strain.
I also describe an original, robust technique for extracting coherence information from conductance fluctuations. The technique is demonstrated in experiments on graphene, used to efficiently detect the presence of magnetic defects. This new approach to studying phase coherence can be easily carried over to other mesoscopic semiconducting systems. === Science, Faculty of === Physics and Astronomy, Department of === Graduate |
author |
Lundeberg, Mark Brian |
spellingShingle |
Lundeberg, Mark Brian Phase coherence in graphene |
author_facet |
Lundeberg, Mark Brian |
author_sort |
Lundeberg, Mark Brian |
title |
Phase coherence in graphene |
title_short |
Phase coherence in graphene |
title_full |
Phase coherence in graphene |
title_fullStr |
Phase coherence in graphene |
title_full_unstemmed |
Phase coherence in graphene |
title_sort |
phase coherence in graphene |
publisher |
University of British Columbia |
publishDate |
2013 |
url |
http://hdl.handle.net/2429/45614 |
work_keys_str_mv |
AT lundebergmarkbrian phasecoherenceingraphene |
_version_ |
1718584093874061312 |