Abstract
We study the Josephson effect in a quantum spin Hall system coupled to a localized magnetic impurity. As a consequence of the fermion parity anomaly, the spin of the combined system of impurity and spin-Hall edge alternates between half-integer and integer values when the superconducting phase difference across the junction advances by . This leads to characteristic differences in the splittings of the spin multiplets by exchange coupling and single-ion anisotropy at phase differences, for which time-reversal symmetry is preserved. We discuss the resulting -periodic (or ) fractional Josephson effect in the context of recent experiments.
- Received 13 September 2016
DOI:https://doi.org/10.1103/PhysRevLett.117.267001
© 2016 American Physical Society