Quantum Transport in Topological Matter

As the optimization of current semiconductor based computer chip technology reaches its limits, the focus shifts towards development of novel techniques that have the potential to revolutionize the computer industry. Low-power electronics, high-density information storage and quantum computing all require extensive research into suitable materials. In this thesis, I present fundamental research on the physical properties of strongly correlated and topological materials, which are candidates to become the fundamental building blocks of a new generation of electronics. Through magnetotransport measurements, conductance spectroscopy and measurement of the inverse AC Josephson effect, we gain important information about the electronic structure of complex oxides and Dirac semimetals. Based the results, several conclusions come to light. First of all, while the LaAlO3/SrTiO3 system may not be used as the functional part of future electronics, the results of this thesis demonstrate that the material is undoubtedly highly interesting and serves as an interesting platform for fundamental research into the interplay of intriguing phenomena. Furthermore, the 3D Dirac semimetal BiSb3% has proven to exhibit the exotic properties that Dirac materials are expected to contain. Using these properties, we show that Majorana zero modes can be detected as 4π-periodic bound states in S-DSM-S Josephson junctions. These signs of topological superconductivity are not restricted to artificially constructed devices, but may in principle also exist in nature. To this end, we investigate whether superconductor and Dirac semimetal PdTe2 shows signs of topological superconductivity, but conclude that this is not the case, so that for now the focus remains on artificially engineered materials for the utilization of topological superconductivity. To make the transition from fundamental proof-of-principle applications (such as described in this work) to functional electronics, as seen from an engineering perspective, high quality thin films are required.