Abstract
Surface states of topological insulators feature chiral spin-momentum locking. When such states are used as weak link between two superconductors, their spin texture gives rise to the anomalous Josephson effect, i.e., to a 𝜑0 shift in the current phase relation. In this work, we explore the anomalous Josephson effect in junctions where the weak link is a HgTe nanowire. We observe a giant anomalous 𝜑0-shift of the current-phase relation, which we attribute to the fact that HgTe surface states feature a single Fermi contour. Moreover, by varying the orientation of the in-plane magnetic field, we obtain information about the spin texture in momentum space. In particular, we found that the spin is not exactly perpendicular to the momentum, but shows a significant deviation of 19 degrees. Our results establish the anomalous Josephson effect as a sensitive tool to probe the spin texture of chiral 2D systems.
N. Hüttner, A. Costa, L. Tosi, M. Barth, W. Himmler, D. A. Kozlov, L. Golub, N. N. Mikhailov, K. Richter, D. Weiss, C. Strunk, & N. Paradiso. Giant anomalous Josephson effect as a probe of spin texture in topological insulators. arXiv preprint arXiv:2601.20410 (2026) https://doi.org/10.48550/arXiv.2601.20410