Planar Tunneling and Andreev Bound State Spectroscopy of YBa2Cu3O7- d Thin Films Using Solution-Deposited Zirconia Insulators
Hentges, Patrick Jay
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https://hdl.handle.net/2142/34744
Description
Title
Planar Tunneling and Andreev Bound State Spectroscopy of YBa2Cu3O7- d Thin Films Using Solution-Deposited Zirconia Insulators
Author(s)
Hentges, Patrick Jay
Issue Date
2004-10
Doctoral Committee Chair(s)
Greene, Laura H.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Superconductors
YBCO Thin Film
Tunneling Measurements
Language
en
Abstract
Planar tunnel spectroscopic measurements are performed on YBa2Cu3O7-δ (YBCO) thin films at four different crystallographic orientations. Since tunneling is a highly surface-sensitive probe on YBCO, films have been optimized for high surface quality. To fabricate the tunneling insulator, a novel fabrication technique has been developed through solution condensation and hydrolysis of zirconia, which has proven to be gentler to the surface than previous techniques. The result is a clean tunneling interface as shown in scanning electron microscopy, atomic force microscopy and transmission electron microscopy, that allows us to detect several new features in the tunneling conductance.
In addition, we have fabricated tunnel junctions with three different counter-electrode deposition techniques. In doing so, various behaviors of the tunneling conductance and its dependence on magnetic field, temperature, and injected current as a function of these counter-electrode deposition techniques has been observed. Modeling of the tunneling conductance has provided insight into the various behaviors. It has been shown that by varying the value of the tunneling cone, surface faceting and quasiparticle lifetime, in agreement with the observations, splitting vs. non-splitting of the zero-bias conductance peak can be understood.
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