Scanning probe microscopy with SQUID-on-tip sensor

In this thesis, we present the work developed in the past four years, on the fabrication, improvements and applications of a promising scanning probe technique, based on the SQUID technology. The nanoSQUID sensors improved drastically, but most of them lie on the plane of a large substrate and are therefore complicated to apply as scanning sensors. Although there have been demonstrations of magnetic imaging by scanning samples in proximity to such SQUIDs, the geometry is not amenable to a generally applicable microscopy. The nanoSQUIDs, that we used for our investigations, unlike conventional planar SQUIDs, can have diameters down to 50nm and are positioned on the apex of a sharp tip, hence their name a SQUID-on-tip (SOT).