Superconductivity in reduced dimensions
Abstract/Contents
- Abstract
- This thesis covers three different superconducting systems. One dimensional aluminum rings, and two dimensional heterostructures of LaAlO3/SrTiO3 and ß-doped SrTiO3. In all cases we studied the magnetic response of these superconductors using a scanning SQUID microscope. In our study on 1D aluminum rings, we monitor the magnetic response of the persistent supercurrent to explore the impact of phase fluctuations on the ring's ability to screen magnetic fields. The physical parameters of the rings were designed to reduce the superconducting phase stiffness. We observe a suppression of the susceptibility signal below the critical temperature, which we attribute to a thermodynamic sampling of metastable states with different phase winding number, termed fluxoid fluctuations. We find our data is well descried by a simple theoretic model wich accounts for a thermodynamic sampling of fluxoid states. The next part of the thesis discusses two dimensional superconductors at the interface of complex sides. In LaAlO3/SrTiO3, we discovered nanoscale patches of magnetism coexisting with inhomogeneous superconductivity. We analyze the magnetic field from the magnetic patches and find it is not large enough to be responsible for the inhomogeneity observed in the superconductivity. Instead, we found that a landscape of isolated paramagnetic spins is the driving source of the inhomogeneity. The gate tunable nature of the LAO/STO interface provides an additional avenue for studying the superconductivity. Our measurements of the temperature dependence of the superfluid density, taken at different gate voltages, collapse to a single curve characteristic of a full superconducting gap. This indicates that superconductivity in this exotic system may be conventional in nature. Finally, we measured the temperature dependence of the superfluid density of ß-doped STO using two different techniques and show that it is also a conventional superconductor.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2012 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Bert, Julie Ann |
|---|---|
| Associated with | Stanford University, Department of Physics |
| Primary advisor | Moler, Kathryn A |
| Thesis advisor | Moler, Kathryn A |
| Thesis advisor | Hwang, Harold Yoonsung, 1970- |
| Thesis advisor | Kivelson, Steven |
| Advisor | Hwang, Harold Yoonsung, 1970- |
| Advisor | Kivelson, Steven |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Julie A. Bert. |
|---|---|
| Note | Submitted to the Department of Physics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2012. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2012 by Julie Ann Bert
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