Measurements of superconducting phase gradients by a nanowire quantum interference device templated by DNA molecules
Hopkins, David Scott
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https://hdl.handle.net/2142/31389
Description
Title
Measurements of superconducting phase gradients by a nanowire quantum interference device templated by DNA molecules
Author(s)
Hopkins, David Scott
Issue Date
2006
Doctoral Committee Chair(s)
Bezryadin, Alexey
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
superconducting nanowires
Language
en
Abstract
Previously employed wet-chemistry approaches to DNA metallization from
granular wires that become highly resistive at low temperatures. We have developed a
process to make superconducting nanowires templated by DNA molecules that are
homogeneous, are less than 10 nm in diameter, make seamless contacts the leads, and
become superconducting at low temperatures. Our method involves isolating single
DNA strands stretched across a narrow but deep trench and sputter-coating MoGe on the
DNA scaffold. We have used these nanowires as the basis for a quantum interference
device in which two wires are connected in parallel by superconducting films. We have
discovered resistance oscillations for the two-wire device as a function of phase gradients
in the leads caused by magnetic screening currents or applied currents, and we have
developed a theory to explain our observations based on an extension of the Langer-
Ambegaokar-McCumber-Halperin theory of thermally activated phase slips. In addition,
we also measure the effect of vortex motions on these oscillations and confirm the field
dependence of the Campbell penetration depth.
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