Point-contact spectroscopy in novel materials
Abstract/Contents
- Abstract
- This thesis describes point-contact spectroscopy (PCS) experiments on BaPb$_{1-x}$Bi$_x$O$_3$ (BPBO) and KWO$_3$ with both an aluminum tip to probe the tunneling regime and a gold tip to probe the Andreev regime. In the case of BPBO, when in the tunneling regime, we find a suppression in the density of states above the transition temperature which has not been previously commented about in the literature. With further support from resistivity measurements, we conclude that a disorder-driven metal insulator transition is present in this material which seemingly occurs before the onset of the charge-disproportionated charge density wave. We suggest that a scaling theory might be applicable to our tunneling results. We also present a method to estimate the transition temperature without disorder. When using a gold tip, we find that the coherence peaks are larger than can be fit with traditional Blonder-Tinkham-Klapwijk theory and more theoretical work is needed to describe results in this low tunneling barrier limit. Preliminary PCS of KWO$_3$ with a Au tip display some results with a suppression in the density of states around zero-bias above the transition temperature as well. Given the high residual resistivity of this material, we thought that disorder was also a likely factor in this material. Hence we decided to measure KWO$_3$ with an Al tip to probe the tunneling regime. However, surprisingly the junction resistance was too low to probe the tunneling regime. While more experiments are necessary to uncover whether disorder plays a major role in this material, we apply similar calculations as in BPBO to measure the disorder-free critical temperature and find that this provides further support to the disorder claim.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2013 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Luna, Katherine |
|---|---|
| Associated with | Stanford University, Department of Physics. |
| Primary advisor | Beasley, Malcolm |
| Thesis advisor | Beasley, Malcolm |
| Thesis advisor | Devereaux, Thomas Peter, 1964- |
| Thesis advisor | Fisher, Ian R. (Ian Randal) |
| Advisor | Devereaux, Thomas Peter, 1964- |
| Advisor | Fisher, Ian R. (Ian Randal) |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Katherine Luna. |
|---|---|
| Note | Submitted to the Department of Physics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2013. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2013 by Katherine Ellen Luna
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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