Engineered Tunnel Barriers for a YBCO Single Electron Transistor
Examensarbete för masterexamen
https://hdl.handle.net/20.500.12380/302177
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Master thesis-Zenas Van Veldhoven (2014).pdf | 4.02 MB | Adobe PDF | ![]() |
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Type: | Examensarbete för masterexamen |
Title: | Engineered Tunnel Barriers for a YBCO Single Electron Transistor |
Authors: | Van Veldhoven, Zenas |
Abstract: | Despite the great scienti c effort, the microscopic origin of superconductivity in the high-temperature superconductor Y Ba2Cu3O7-8 is still not understood. In recent work, Gustafsson, D. et al. discovered that the superconducting order parameter in a Y Ba2Cu3O7-8 mesoscopic island did not have a purely d-wave symmetry, as it is commonly assumed. By using a Single-Electron Transistor (SET) made of a Y Ba2Cu3O7-8 source, mesoscopic island, drain and gate, they discovered that the Y Ba2Cu3O7-8 island had a fully gapped superconductivity. This indicates the existance of a subdominant imaginary order parameter in Y Ba2Cu3O7-8 that gaps the nodes of the d-wave order parameter. In order to investigate the doping dependence of this subdominant order parameter, one should use a new design for the SET, with normal metal source, drain and gate. To have a working SET, the tunnel resistance between the electrodes and the islands needs to be higher than the quantum resistance. The goal of this work is to engineer the Y Ba2Cu3O7-8-Au tunnel junction with a su - ciently high tunnel resistance. For that, tunnel barriers between Y Ba2Cu3O7-8 and Au were created by an Ar ion milling procedure of the surface using different etching times and di erent voltages. The current-voltage characteristics of the Au-Y Ba2Cu3O7-8 junctions were investigated and the contact resistivity between Y Ba2Cu3O7-8 and Au was measured. The surface etching seems to create low transparency interfaces. In addition, a normal Y Ba2Cu3O7-8 layer is formed at the surface, which can be turned superconducting by ozone treatment. Suitable tunnel barriers for a Y Ba2Cu3O7-8 SET can be created using mild surface etching and ozonation. |
Issue Date: | 2021 |
Publisher: | Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap (MC2) |
URI: | https://hdl.handle.net/20.500.12380/302177 |
Collection: | Examensarbeten för masterexamen // Master Theses |
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