ELFT HÍRADÓ

[Makk Péter <peter.makk AT gmail.com>]

 Kedves kollégák!

Mindenkit szeretettel meghívunk a Fizika tanszék szemináriumára:

Előadó: Christoph Strunk (Uni. Regensburg).
Cím: Dc-current stimulated superfluid density in strongly disordered
two-dimensional superconductors

Hely: BME Elméleti Fizika tanszék szemináriumi szoba, BME F III.
magasföldszint 01
Időpont: Nov. 15, Hétfő, 10:15

A szeminárium hibrid formátumú, online itt lehet csatlakozni (MS Teams):
Click here to join the meeting
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Budapest University of Technology and Economics


Absztrakt:
We investigate resistivity and kinetic inductance in ultra-thin NbN near
the superconductor-insulator transition. Resistive transition is dominated
by superconducting fluctuations of both amplitude and phase of the order
parameter. Below the Maki-Thomson and Aslamasov-Larkin fluctuation regimes,
the resistivity displays a square-root cusp divergence of the conductance
expected for the Berezinski-Kosterlitz-Thouless (BKT) transition. At the
same time, kinetic inductance (measured using an RLC-resonator technique)
displays a sharp drop near the universal temperature TBKT.

For the first time, we can directly compare and correlate superfluid
stiffness and transport data on the very same devices. Current voltage (IV)
characteristics become non-linear below TBKT, with a complex back-bending
shape that signals a heating instability. At lower currents and for the
wider samples, we observer the expected power law behavior of I(V) with
exponents close to the expectation for superfluid stiffness.

On the other hand, for the narrower strips, the IV-characteristics feature
a peculiar kink, indicating the onset of enhanced dissipation. This finding
is contrasted by the observation of an unexpected increase of kinetic
inductance close to the critical current that signals a stimulation of
superconductivity by the current.