Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 34: Superconductivity: Tunneling and Josephson Junctions

TT 34.4: Vortrag

Dienstag, 13. März 2018, 10:30–10:45, H 2053

Renormalization of Charging Energy in superconducting Single Electron Transistors — •Susanne Sprenger, Thomas Lorenz, and Elke Scheer — Universität Konstanz

A small island connected by two tunnel junctions and a gate electrode forms a single electron transistor (SET) that shows Coulomb blockade (CB) effects. In the case of weak-coupling, Orthodox Theory (OT) can be used to quantitatively describe the behavior of these devices even when considering superconducting transport [1,2].

Transport in the strong-coupling regime, however, is not yet fully understood and difficult to address with traditional SETs. We present a measurement scheme where all coupling regimes can be addressed. The sample is composed of an AlO_x tunnel barrier and a mechanically controllable break junction, that can be tuned throughout all coupling regimes. When tuning the sample from the orthodox regime to higher couplings the transport properties are changing, which is most prominent in the superconducting state. We observe a renormalization of the charging energy for intermediate couplings as well as the disappearance of the CB for very high couplings, similar to the findings of [3].
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