Regensburg 2025 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 25: Superconductivity: Supercurrent Diode Effect
TT 25.9: Talk
Wednesday, March 19, 2025, 11:45–12:00, H32
Cooper pair diode in Coulomb blockade Pb islands on graphene — •Stefano Trivini1,3, Jon Ortuzar1, Katerina Vaxevani1, F Sebastian Bergeret3,4, and Jose Ignacio Pascual1,2 — 1CICnanogune, Donostia, Spain — 2Ikerbasque, Basque Foundation for Science, Bilbao, Spain — 3Centro de Física de Materiales (CFM),San Sebastián, Spain — 4Donostia International Physics Center (DIPC), Donostia-San Sebastián, Spain
Non-reciprocity, essential for current rectification in electronics, is challenging to achieve in superconducting devices without external magnetic fields. Current methods rely on non-centrosymmetric materials or magnetochiral effects, limiting their versatility. We investigate small Pb islands on graphene where Coulomb and superconducting correlations coexist. Approaching the STM tip to Josephson regimes, we observe Resonant Cooper Pair Tunneling (RCT) peaks in the current-voltage characteristics. RCT values change with gating. We test this in a current-biased STM junction and find a CP current asymmetric with polarity. This is a realization of non-reciprocal transport of CP, tunable with a gate.
Keywords: Coulomb blockade; superconductivity; STM; Josephson Junction; non-reciprocal transport