Imaging current in materials
Abstract/Contents
- Abstract
- Scanning superconducting quantum interference device (SQUID) microscopy is an incredibly sensitive way to image magnetic fields. One application of this technique is to spatially map magnetic fields which originate from moving electrons (i.e. electrical current), and interpret the pattern of current in order to learn more about how electrons behave in interesting materials. In lanthanum aluminate-strontium titanate, two insulators which can host a two-dimensional conducting state at their interface, we discovered locally enhanced conduction due to domain structure in the strontium titanate. 2D topological insulators are a class of materials which are predicted to host special conducting states along the edges of patterned devices, and we were able to image current along the edges of devices in two such materials: HgTe quantum wells and InAs/GaSb quantum wells. In InAs/GaSb, we found that backscattering in the edges was temperature independent and elucidated the presence of edge states in so-called 'trivial' regimes. These results call into question the prevailing interpretation of edge states in InAs/GaSb as topological, and conclude that better experimental evidence is required to definitively identify a 2D topologically insulating state in this material. Finally, we've investigated a fundamental property of Josephson junctions called the current-phase relation in few-mode InAs nanowire junctions. InAs nanowires which are in close contact with conventional superconductors are of great interest due to the possible realization of exotic particles called Majorana quasiparicles which may be of use for quantum computation. We've probed the disorder associated with adding superconductivity to nanowires by measuring the shape of the current-phase relation and finding that it fluctuates as a function of electron density and from junction to junction.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Spanton, Eric M |
|---|---|
| Associated with | Stanford University, Department of Physics. |
| Primary advisor | Moler, Kathryn A |
| Thesis advisor | Moler, Kathryn A |
| Thesis advisor | Goldhaber-Gordon, David, 1972- |
| Thesis advisor | Qi, Xiaoliang |
| Advisor | Goldhaber-Gordon, David, 1972- |
| Advisor | Qi, Xiaoliang |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Eric M. Spanton. |
|---|---|
| Note | Submitted to the Department of Physics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Eric Matthew Spanton
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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