Reconstruction-Induced ${\phi }_0$ Josephson Effect in Quantum Spin Hall Constrictions

Abstract

The simultaneous breaking of time-reversal and inversion symmetry, in connection to superconductivity, leads to transport properties with disrupting scientific and technological potential. Indeed, the anomalous Josephson effect and the superconducting-diode effect hold promises to enlarge the technological applications of superconductors and nanostructures in general. In this context, the system we theoretically analyze is a Josephson junction (JJ) with coupled reconstructed topological channels as a link; such channels are at the edges of a two-dimensional topological insulator (2DTI). We find a robust ${\phi }_0$ Josephson effect without requiring the presence of external magnetic fields. Our results, which rely on a fully analytical analysis, are substantiated by means of symmetry arguments: Our system breaks both time-reversal symmetry and inversion symmetry. Moreover, the anomalous current increases as a function of temperature. We interpret this surprising temperature dependence by means of simple qualitative arguments based on Fermi's golden rule.

13 pages, 3 figures

References in corpus (10)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Nonlocal edge state transport in the quantum spin Hall state
• Direct coupling between magnetism and superconducting current in Josephson Phi junction
• Exotic non-Abelian anyons from conventional fractional quantum Hall states
• Experimental evidence of a ϕ Josephson junction
• Spontaneous breakdown of topological protection in two dimensions
• Spontaneous supercurrent and $\varphi$0 phase shift parallel to magnetized topological insulator interfaces
• Generating and controlling spin-polarized currents induced by a quantum spin Hall antidot
• Effects of the Spatial Extension of the Edge Channels on the Interference Pattern of a Helical Josephson Junction