SKM 2021 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 8: Focus Session: Emerging Phenomena in Superconducting Low Dimensional Hybrid Systems II
TT 8.7: Talk
Tuesday, September 28, 2021, 15:15–15:30, H7
Josephson and Andreev transport in a superconducting single electron transistor with a normal lead (SSN-SET) — •Laura Sobral Rey1,2 and Elke Scheer1,2 — 1Physics department, University of Konstanz, 78464, Konstanz, Germany — 2QuESTech consortium
An island coupled via a tunnel barrier to two leads and a gate forms a single electron transistor (SET) that shows Coulomb blockade. All-superconducting SETs (SSS-SETs) have shown to enable a multitude of possible charge transport processes which are not well understood, in particular in the strong-coupling regime [1]. To disentangle these processes, we study here the conceptually simpler SSN-SET, which has never been investigated experimentally before.
The SSN-SETs studied here consist of an S island coupled to an N lead via an oxide tunnel barrier, and to an S lead with a mechanically controlled break junction (MCBJ). Via the MCBJ, different coupling regimes can be studied: from a tunnel contact when the MCBJ is broken to a point contact when it is closed. In that limit the MCBJ has a small number of highly transmissive transport channels.
For weak coupling, our experimental findings can be understood in terms of the orthodox theory [2]. For stronger coupling, we observe Andreev and Josephson transport, as well as a renormalization of
the charging energy and dynamical Coulomb blockade, which are also observed in the N state.
[1] T. Lorenz, J. Low Temp. Phys. 191, 301 (2017)
[2] T.A. Fulton, Phys. Rev. Lett. 59, 109 (1987)