  Phase winding effects in hollow semiconductor nanowires with superconducting
shells have been proposed as a route to engineer topological superconducting
states. We investigate GaAs/InAs core/shell nanowires with half-shells of
epitaxial aluminium as a potential platform for such devices, where the thin
InAs shell confines the electron wave function around the GaAs core. With
normal contacts we observed pronounced $h/e$ flux periodic oscillations in the
magnetoconductance, indicating the presence of a tubular conductive channel in
the InAs shell. Conversely, the switching current in Josephson junctions
oscillates with approximately half that period, i.e. $h/2e$, indicating
transport via Andreev transport processes in the junction enclosing threading
magnetic flux. On these structures, we systematically studied the gate-,
field-, and temperature-dependent evolution of the supercurrent. Results
indicate that Andreev transport processes can occur about the wire
circumference indicating full proximitization of the InAs shell from the
half-shell superconducting contacts.
