SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 20: Superconductivity: Tunnelling and Josephson Junctions
TT 20.4: Vortrag
Dienstag, 28. März 2023, 10:15–10:30, HSZ 103
Josephson nanojunctions fabricated by He focused ion beam irradiation — •Edward Goldobin1, Max Karrer1, Christoph Schmid1, Katja Wurster1, Ramón Manzorro2,3, Javier Pablo-Navarro2,3, Cesar Magen2,3, Reinhold Kleiner1, and Dieter Koelle1 — 1Physikalisches Institut, Center for Quantum Science (CQ) and LISA+, Universität Tübingen, Germany — 2Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Spain — 3Laboratorio de Microscopías Avanzadas (LMA), Universidad de Zaragoza, Spain
We use a focused He ion beam (He-FIB) for the nanofabrication of Josephson junctions (JJs) and more complex devices based on YBa2Cu3O7−δ (YBCO) thin films [1]. Using an optimum He-FIB irradiation dose, we “write” Josephson barriers across YBCO microbridges. Such JJs have RCSJ-like I–V characteristics, and the dependence of the critical current vs. magnetic field resembles a Fraunhofer pattern. Using higher irradiation doses, we induce insulating regions that can be used for nanopatterning of various circuits, i.e., patterning of SQUID loops, constriction JJs (cJJs), etc.
Investigations of the irradiated regions by scanning transmission electron microscopy (STEM) provide information on the modification of the crystalline structure of YBCO on the atomic scale. STEM analysis reveals the amorphization thresholds for irradiation of 1D and 2D patterns (depending on the beam size), and provides insights into the current resolution limits for the fabricaton of YBCO cJJs.
[1] B. Müller et al., Phys. Rev. Applied 11, 044082 (2019)