Oral: Nanoscale SQUIDs on chip for high-resolution magnetic imaging

Scanning quantum interference device (SQUID) microscopy enables local imaging of current distributions and the magnetic responses of quantum materials. Typical tunnel junction SQUID designs only tolerate external magnetic fields less than about 10 mT, and have a spatial resolution of about 1 μm or more. We report on fabrication of niobium SQUIDs with superconducting weak links patterned by electron beam lithography in a planar geometry. These devices may be fabricated with submicron spatial resolution and operate in magnetic fields exceeding 0.5 T. This approach allows for the fabrication of additional on-chip circuitry, such as an integrated field coil for measuring local magnetic susceptibility, which would be more difficult in other fabrication methods that directly pattern the SQUID on a quartz pipette tip or silicon cantilever.