Current imaging is crucial to condensed matter physics, materials research and industry. State-of-the-art current imaging setups revolve around SQUID-on-tip (SOT) probes, that scan over a sample to...Show moreCurrent imaging is crucial to condensed matter physics, materials research and industry. State-of-the-art current imaging setups revolve around SQUID-on-tip (SOT) probes, that scan over a sample to locally measure magnetic fields and temperature. The resolution of such systems is presently limited by the lack of a robust method to control the probe-sample distance. In this thesis, we develop probes for hybrid microscopy that combine SOT with STM. We theoretically investigate interesting systems, and find that our approach would considerably improve on past magnetic investigations of vortex matter. We use focused-ion-beam milling to fabricate SOT probes on top of a commercial AFM-cantilever, and show these to be very sensitive to changes in applied magnetic field and temperature. We develop a novel readout scheme to simultaneously measure a magnetic and a tunneling signal. We present a proof-of-concept STMSOT probe that displays magnetic sensitivity inside a cryogenic STM setup, and use it as an STM probe to see the topography of a NbSe$_2$ crystal. Our approach will culminate in the development of a STMSOT setup in the near future.Show less
In order to curb the growing energy demand and environmental impact of data centers, breakthrough technologies bringing increased energy efficiency are required. Superconducting computing promises...Show moreIn order to curb the growing energy demand and environmental impact of data centers, breakthrough technologies bringing increased energy efficiency are required. Superconducting computing promises massive energy savings through near-dissipationless operation. So far, multiple designs for superconducting memory are proposed, but none meets all requirements for an implementable device. To this end, we propose a novel design of superconducting memory (SCM) device, using two stable magnetic spin textures in a single-layer elliptical SFS Josephson junction. We observe a change in critical current between the two states by a factor of five at remanence. Using a novel technique to quantify the effects of stray fields using micromagnetic simulations, we conclude that the shift in critical current is caused by a large contrast in stray field strength between the two magnetic states. Furthermore, we verify that the switching process is deterministic and unambiguous during read-out. Future pathways to scale up this memory device are proposed.Show less
Focused electron-beam induced deposition (FEBID) is a non-destructive, relatively fast and cheap method with applications in AFM, plasmonics and nanomagnetics amongst others. In this thesis, three...Show moreFocused electron-beam induced deposition (FEBID) is a non-destructive, relatively fast and cheap method with applications in AFM, plasmonics and nanomagnetics amongst others. In this thesis, three dimensional superconducting arches were fabricated using this technique with the help of a computer aided design (CAD) program. Magnetic field sweeps were performed at low temperatures (∼2-5 K) to characterize these arches. With a few improvements, more complex 3D structures can be fabricated, paving the way towards the numerous applications people now can only dream of.Show less
Superconducting QUantum Interference Devices (SQUIDs) play a central role in numerous applications, ranging from cancer treatment to magnetic imaging of nanoparticles. Conventional fabrication...Show moreSuperconducting QUantum Interference Devices (SQUIDs) play a central role in numerous applications, ranging from cancer treatment to magnetic imaging of nanoparticles. Conventional fabrication methods revolve around a multi-step lithography process that encompasses etching, heating, chemical cleansing and coating, thereby limiting these techniques in practice. In this thesis we present a non-destructive alternative approach that does not entail pre- or post processing, namely, a direct-write printed SQUID patterned under 20 minutes using Focus Electron Beam Induced Deposition (FEBID). The Josephson behaviour of these devices is confirmed by performing out-of-plane magnetic field sweeps and measuring the corresponding oscillations in critical current. Our endeavours pave the way for printing sophisticated quantum systems and three dimensional superconducting sensors.Show less
The family of rare-earth nickelates (RNiO3. R = La, Pr, ..., Lu) show a sharp metal-insulator transition from a paramagnetic metal to an anti-ferromagnetic insulator. The only exception is LaNiO3...Show moreThe family of rare-earth nickelates (RNiO3. R = La, Pr, ..., Lu) show a sharp metal-insulator transition from a paramagnetic metal to an anti-ferromagnetic insulator. The only exception is LaNiO3 which is a paramagnetic metal even at low temperatures. Thin films of LaNiO3 do show a metal-insulator transition when reducing the film thickness to only a few unit cells. In this study we track the electronic structure of (001) oriented LaNiO3 thin films as they go from a metallic to an insulating state. We observe this transition occurring at a thickness of 4 unit cells. The very high resolution of our ARPES set-up allows us to resolve the inelastic mean free path changing with film thickness. We find that the mean free path mimics the reported resistivity behaviour. We also find a pseudogap opening in the insulating state.Show less
