The current through a Josephson junction is governed by the current-phase relation (CPR) that depends on the phase difference between the electrodes. Notable applications are qubits, Josephson...Show moreThe current through a Josephson junction is governed by the current-phase relation (CPR) that depends on the phase difference between the electrodes. Notable applications are qubits, Josephson diodes and microscopic imaging techniques. This thesis presents a method to measure the CPR based on [1]. The junction under study is incorporated into a superconducting loop that is inductively coupled to a dc-SQUID magnetometer. The measured flux is proportional to the junction’s phase and by controlling the current through the junction’s loop it is possible to directly measure the CPR. This thesis outlines several important considerations and constraints of this method. Furthermore we provide CPR measurements of a superconductor-normal- superconductor (SNS) junction made from Nb and Cu. It shows a clear temperature dependence with a qualitative change in shape as well as a quantitative change in amplitude of the current-phase relation. These results are in agreement with theory. In the future a flux-locked loop can be used to further improve the measurements.Show less
In this work, we use electron-beam-induced deposition (EBID) to create superconducting structures. This is then applied in the fabrication of superconducting devices, which are characterized in low...Show moreIn this work, we use electron-beam-induced deposition (EBID) to create superconducting structures. This is then applied in the fabrication of superconducting devices, which are characterized in low-temperature experiments.Show less
In this report, we discuss the possibility to use Josephson junctions as superconducting memory devices. These Josephson junctions are SFS (Superconductor-Ferromagnet-Superconductor) junctions. Due...Show moreIn this report, we discuss the possibility to use Josephson junctions as superconducting memory devices. These Josephson junctions are SFS (Superconductor-Ferromagnet-Superconductor) junctions. Due to a magnetization gradient, we generate triplet supercurrent at the interface. The junctions are disk-shaped, with cobalt on the bottom as the ferromagnet and niobium on top as the superconductor. Through the niobium, a trench is milled, to create the junction. The magnetization of the cobalt is circular in a pattern called a vortex. In the center the magnetization comes out of the plane. This is called the vortex core, and splits the junction into two channels. We can push this vortex core out with an in-plane field. By measuring out-of-plane interference patterns, we can calculate the spatial supercurrent distribution. By measuring such patterns with and without the vortex, we have shown that these SFS Josephson junctions can be used as superconducting memory devices.Show less
In this thesis we present our research on two triplet superconductors in two distinct systems. The first part of this report is concerned with SRO, a leading candidate for p-wave chiral pairing,...Show moreIn this thesis we present our research on two triplet superconductors in two distinct systems. The first part of this report is concerned with SRO, a leading candidate for p-wave chiral pairing, where the aim is to develop an efficient method to fabricate mesoscopic structures suitable for investigating confinement effects. A number of top-down techniques are implemented to obtain micron-sized crystals that can be readily structured and contacted for transport measurements. We show that tape exfoliation, similar to the scotch tape method, can be used to achieve the desired results. The second part of this report deals with triplet superconductivity in Superconductor-ferromagnet hybrids. In particular, we investigate the behavior of a Josephson junction located in a ferromagnetic disk. Applying the model developed by Dynes & Fulton [1] critical current density across the junction is estimated. We show that the triplet supercurrent is split into two distinct channels defined by the micromagnetics of the disk.Show less
