The pairing symmetry of the superconducting material Strontium Ruthenate (Sr2RuO4), despite much research, has not been established. The experimental evidence until now points to a pairing symmetry...Show moreThe pairing symmetry of the superconducting material Strontium Ruthenate (Sr2RuO4), despite much research, has not been established. The experimental evidence until now points to a pairing symmetry compatible with the existence of superconducting domains. The boundaries of these domains are expected to act as Josephson junctions. Although bulk samples contain a random and non-predictable domain structure, mesoscopic samples feature a controllable configuration of the domains. The behavior of singly or doubly presupposed connected domain boundary is investigated by the electronic transport properties of mesoscopic samples of Sr2RuO4, in which the domain walls are pinned to the geometry. The characteristic critical current oscillations and Shapiro steps of the Josephson junction are established, as well as current switchable states due to in-plane (IP) fields.Show less
This work presents a study of two types of spin-triplet Josephson junctions that are characterised by superconducting quantum interference and Shapiro step measurements. The first type of system is...Show moreThis work presents a study of two types of spin-triplet Josephson junctions that are characterised by superconducting quantum interference and Shapiro step measurements. The first type of system is a cobalt/niobium disk where long-range triplets are generated by the spin texture of a ferromagnetic vortex. The second system is a mesoscopic ring of Sr2RuO4, which is expected to host intrinsic Josephson junctions by the presence of chiral domain walls. For the cobalt/niobium disk, two supercurrent channels have been found surprisingly close to the edges of the disk by quantum interferometry measurements while indications of 0-pi segments have been found by the observation of half-integer Shapiro steps. Two rings with different inner and outer radii of Sr2RuO4 are shown to behave as Josephson junctions. The configurations of these junctions depend on the ring dimensions and the temperature. These findings make a convincing case for the presence of chiral domains in Sr2RuO4.Show less
Sr2RuO4 is a leading candidate for equal-spin triplet pairing with p-wave chiral symmetry. This study presents a method for fabricating mesoscopic structures of Sr2RuO4. The samples are contacted...Show moreSr2RuO4 is a leading candidate for equal-spin triplet pairing with p-wave chiral symmetry. This study presents a method for fabricating mesoscopic structures of Sr2RuO4. The samples are contacted by conventional electron beam lithography methods. A measurement set-up using a vector magnet cryostat was prepared for transport measurements. We observe a high residual resistance ratio indicating high sample quality. The onset of signs of superconductivity appear at 1.5 K, as expected. Crystals with a thickness below 20 nm are found to be insulating, the origin is currently not understood.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
