Nanoscale multifunctional sensor formed by a Ni nanotube and a scanning Nb nanoSQUID

Nanoscale magnets might form the building blocks of next generation memories. To explore their functionality, magnetic sensing at the nanoscale is key. We present a multifunctional combination of a nanometer-sized superconducting quantum interference device (nanoSQUID) and a Ni nanotube attached to an ultrasoft cantilever as a magnetic tip. By scanning the Nb nanoSQUID with respect to the Ni tube, we map out and analyze their magnetic coupling, demonstrate the imaging of an Abrikosov vortex trapped in the SQUID structure — which is important in ruling out spurious magnetic signals — and reveal the high potential of the nanoSQUID as an ultrasensitive displacement detector. Our results open a new avenue for fundamental studies of nanoscale magnetism and superconductivity.