CrO2, a half-metal ferromagnet, has shown great promise for superconducting spintronics applications for nearly two decades. Josephson junctions consisting of superconducting (S) contacts on... Show moreCrO2, a half-metal ferromagnet, has shown great promise for superconducting spintronics applications for nearly two decades. Josephson junctions consisting of superconducting (S) contacts on ferromagnetic (F) structures of CrO2, have been shown to sustain remarkably high supercurrents over hundreds of nanometers. However, advancements in this area have been hindered by the metastable nature of CrO2 at ambient conditions. This results in a poorly controlled S-F interface transparency, which is critical for generation of spin triplets. This thesis explores the potential, challenges and possible solutions to overcome the issues with CrO2 devices. Show less
We find ourselves in an era of transition, not just towards a more computing- and data-driven society but also away from unsustainable fossil fuels as an energy source. This leads to a rapidly... Show moreWe find ourselves in an era of transition, not just towards a more computing- and data-driven society but also away from unsustainable fossil fuels as an energy source. This leads to a rapidly increasing demand for computing power on an ever more tight energy budget. Therefore, it is imperative to investigate novel energy-efficient computing techniques, like superconducting spintronics or neuromorphic computing using correlated electron matter. Naturally, understanding the physics governing these processes at the sub-micrometer (i.e., device) scale is crucial for this development to succeed. This thesis examines the effects of size reduction and geometry on ferromagnetic Josephson junctions and highly correlated electron matter through transport experiments. Specifically, it describes how spin-polarized supercurrents can be generated using spin texture, stabilized by carefully tuning the geometry of planar Josephson junctions, and how the bistability of these spin textures can be employed to create non-volatile superconducting memory elements. Furthermore, it reports a strong size dependence of the current density that drives the Mott-insulating-to-metal transition in Ca2RuO4 and shows how various constricted geometries can be used to localize and examine the properties of superconducting chiral domain walls in Sr2RuO4. Show less
In this thesis we study quantum transport phenomena on the nanometer scale, in two classes of materials: topological insulators with induced superconductivity and graphene superlattices. Both... Show moreIn this thesis we study quantum transport phenomena on the nanometer scale, in two classes of materials: topological insulators with induced superconductivity and graphene superlattices. Both topics are motivated by recent experimental developments: the first topic arose from the search for Majorana fermions in a quantum spin Hall insulator, the second topic arose from the search for massive Dirac fermions in the Kekulé band structure of graphene on a copper substrate. We focus on lattice models, solving them both numerically and analytically. Show less
