Berlin 2024 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 18: Superconductivity: Poster
TT 18.32: Poster
Monday, March 18, 2024, 15:00–18:00, Poster C
YBa2Cu3O7 constriction-type Josephson junctions with integrated shunt resistors fabricated by focused-helium-ion-beam irradiation. — •Christoph Schmid1, Moritz Meichsner1, Dominik Hanisch2, Max Pröpper2, Meinhard Schilling2, Edward Goldobin1, Dieter Koelle1, and Reinhold Kleiner1 — 1Physikalisches Institut, Center for Quantum Science and LISA+, Universität Tübingen — 2Institut für Elektrische Messtechnik und Grundlagen der Elektrotechnik, Technische Universität Braunschweig
We report on the investigation of YBa2Cu3O7 (YBCO) Josephson junctions (JJs) fabricated by irradiation with a focused helium ion beam (He-FIB). With this method one can locally modify YBCO thin films, to write insulating or normal conducting regions, including Josephson barriers, depending on the He-FIB irradiation dose D. We investigated the electric properties of YBCO areas with typical lateral size of 30× 2000 nm2, irradiated with D∼ 40 ions/nm2. Such a dose preserves the YBCO crystal structure but supresses the critical temperature Tc completely. Thus, such areas can be used as shunt resistors with dose-dependent resistivity and ohmic I−V characteristics (IVCs). Moreover, we created constriction-type JJs (cJJs) between resistive areas. By constricting the cJJ width down to 6 nm, we observe resistively-shunted-junction (RSJ) like IVCs with small excess currents and characteristic voltages of 3 – 60 mV, making such JJs interesting for high-frequency applications. Our fabrication method opens a way to fabricate nano-circuits with integrated nm-sized cJJs and resistors/resistive areas during a single He-FIB irradiation process.
Keywords: Constriction Josephson junction; YBCO; He FIB