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TT: Fachverband Tiefe Temperaturen
TT 14: Superconductivity: Properties and Electronic Structure
TT 14.2: Vortrag
Montag, 9. März 2026, 15:15–15:30, HSZ/0103
Two facets of kinetic inductance in Corbino reflectometry on disordered and granular superconductors — •Jan Pusskeiler1, Martin Dressel1, Thomas Valentin2, Ameya Nambisan2, Simon Geisert2, Ioan Pop1,2, Christoph Strunk3, Dennis Rieger4, and Marc Scheffler1 — 11. Physikalisches Institut, Universität Stuttgart — 2Physikalisches Institut and IQMT, KIT — 3Institut für Experimentelle und Angewandte Physik, Universität Regensburg — 4Qinu GmbH, Karlsruhe
Kinetic inductance Lkin manifests as a linear-in-frequency contribution to the reactance, which determines the low-temperature electrodynamics of superconducting microwave circuitry. We directly probe this inductive response from MHz- to GHz-frequencies, Im(Z) = ω · Lkin , by broadband microwave reflectometry on superconducting granular aluminum and titanium nitride in the Corbino geometry. Furthermore, we identify an unconventional collective mode with a phase velocity governed by Lkin. We observe an acoustic dispersion relation for up to 10 harmonics, which enables us to obtain the kinetic inductance independently for both phenomena observed in one spectrum.
We report low-temperature kinetic inductances ranging from 20 pH/ to 2 nH/ for granular aluminum and up to 6.2 nH/ for titanium nitride thin films, with critical temperatures Tc ranging from 1 K to 3 K. We calculate the low-temperature superfluid stiffness J0 and observe its suppression with increased normal-state resistivity ρn. For both materials in regimes with large ρn, we find that J0 converges to Tc, consistent with a phase-driven superconducting transition.
Keywords: kinetic inductance; granular aluminum; disordered superconductors; microwave Corbino reflectometry; unconventional collective modes