Topological insulator based axial superconducting quantum interferometer structures

Nanoscale superconducting quantum interference devices (SQUIDs) are fabricated in-situ from a single Bi${}_{0.26}$Sb${}_{1.74}$Te${}_3$ nanoribbon that is defined using selective-area growth and contacted with superconducting Nb electrodes via a shadow mask technique. We present $h\mathrm{/}(2e)$ magnetic flux periodic interference in both, fully and non-fully proximitized nanoribbons. The pronounced oscillations are explained by interference effects of coherent transport through topological surface states surrounding the cross-section of the nanoribbon.