Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 97: Superconducting Diodes and Ratchets
TT 97.2: Talk
Friday, March 13, 2026, 09:45–10:00, CHE/0089
Giant anomalous Josephson effect as a probe of spin texture in topological insulators — Niklas Hüttner1, Andreas Costa1, Leandro Tosi2, Michael Barth1, Wolfgang Himmler1, Dmitriy A. Kozlov1, Leonid Golub1, Klaus Richter1, Jaroslav Fabian1, Dieter Weiss1, Christoph Strunk1, and •Nicola Paradiso1 — 1University of Regensburg, Germany — 2Grupo de Circuitos Cuánticos, Bariloche, Argentina
Topological-insulator surface states are chiral 2D electron systems with spin-momentum locking. Josephson junctions based on such states show nonreciprocal supercurrent features if time reversal symmetry is broken. For example, they show a finite phase at zero current, i.e., an anomalous Josepshon effect. I will present ϕ0 measurements on junctions with HgTe nanowires as weak link. We detect an exceptionally large anomalous phase shift in the current-phase relation. We attribute this giant ϕ0-shift to the single Fermi-surface contour of HgTe surface states, a key distinction from Rashba systems with two counteracting Fermi contours. By rotating the in-plane magnetic field, we probe the spin texture in momentum space. Interestingly, we find that the spin deviates by 19 degrees from the orientation perpendicular to the momentum. Our findings demonstrate that the anomalous Josephson effect provides a powerful and sensitive probe of the spin texture in chiral two-dimensional systems.
Keywords: anomalous Josephson effect; Rashba spin-orbit; HgTe; nonreciprocal superconductivity; spin texture