Flux-periodic resistance oscillations in arrays of superconducting weak links based on InAs-AlSb quantum wells with Nb electrodes

InAs-AlSb quantum wells contacted with periodic gratings of superconducting Nb electrodes show Josephson-junction characteristics at low temperatures. When a nonzero resistance is reestablished by a weak magnetic field, the resistance shows a strong component periodic in the magnetic field. At fields above ∼300 μT, the oscillation period corresponds to one flux quantum per grating cell; but in wide arrays (≳40 μm), a frequency doubling takes place at low fields, indicating the formation of a staggered vortex superlattice at twice the lithographic period.