Influence of localization and interaction on charge transport in graphene
Date Issued
2015
Date
2015
Author(s)
Ho, Yi-Fan
Abstract
There are two subjects in this thesis. In the first part, I will report our study on the low temperature resistance properties of hydrogen-intercalated epitaxial graphene. Graphene is a fantastic material with lots of special properties. By means of hydrogen intercalation, the interaction between the substrate and graphene is reduced. At low temperatures, except the classic Drude conductivity, there are two quantum corrections: electron-electron interactions (EEI) and weak localization (WL). EEI and WL have different magnetic dependences. To study these two different properties ranges, we measured the sample in the low field and high field regime. The analysis shows that the prefactor of EEI is dependent of magnetic field, which need to be further studied. Second, we focused on the type-II superconductor. Superconductors can have no resistance below a critical temperature. This wonderful property has drawn many attentions. Type-II superconductor has higher critical temperature and has different magnetic properties compare to type-I superconductor. The proximity effect on YBCO-graphene-YBCO (SGS) junction was studied. We were interested in supercurrent in this SGS junction below the YBCO’s critical temperature. We successfully transferred a CVD graphene on the gap of the bridge. However, we did not observe the supercurrent in the junction. To improve the interface between superconductor and graphene and quality of the graphene, current anneal method was utilized, but had a limited effect.
Subjects
High critical temperature superconductor
graphene
weak localization
Electron-electron interactions
Josephson Effect
Type
thesis
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