Scanning SQUID-on-tip (SOT) microscopy offers topographic, magnetic and thermal imaging at high sensitivities. This project focused on the development of a SOT from a self-sensing, self-actuating...Show moreScanning SQUID-on-tip (SOT) microscopy offers topographic, magnetic and thermal imaging at high sensitivities. This project focused on the development of a SOT from a self-sensing, self-actuating tuning fork AFM probe. Patterning the superconducting contacts to the SQUID was identified as the main challenge. The non-planar geometry of the probe discourages continuous film growth and prohibits the use of lithography to pattern the film. The superconducting element of the SOT must be electrically isolated from the adjacent tuning fork actuation circuit. Off-axis sputtering of 60nm NbTi was found to minimize short circuits and result in continuous superconducting films. The steps necessary to pattern the NbTi film were identified; Off-axis sputtering at a slight incline with respect to the deposition substrate and a better-fitting micromachined hard mask will enable the fabrication of a SOT atop a tuning fork AFM probe.Show less
Magnetic imaging plays an essential part in measuring magnetic sources, whether they are nanoparticles, superconductor vortices, edge currents, or something else. Current techniques either lack the...Show moreMagnetic imaging plays an essential part in measuring magnetic sources, whether they are nanoparticles, superconductor vortices, edge currents, or something else. Current techniques either lack the necessary sensitivity and spatial resolution or are too invasive to use in many applications. Scanning SQUIDs are non-invasive and have excellent sensitivity, but operate at a large distance from the surface. By integrating a SQUID into a Scanning Tunneling Microscopy (STM) we will be able to image magnetic sources within 1 nm from the surface, increasing its sensitivity and spatial resolution. It also allows us to simultaneously gather topographic information, something no other scanning SQUID can do. To achieve this, a new production method is developed to create a SQUID on top of a sharp tip. To get a continuous superconducting connection across the surface of the tip, Molybdenum Germanium is used as a superconductor, with silver SNS junctions to prevent hysteresis. Measurements on larger MoGe-Ag SQUIDs show that this design could achieve a theoretical spin sensitivity of 1μB/√Hz at 4.2 K, with a spatial resolution of 30 nm.Show less
