Research Projects

The recent discovery of Superconducting diode effect (SDE) in non-centro symmetric superconductors with finite-momentum Cooper pairing, often called as nonreciprocity of supercurrent, attracted intensive interest in condensed matter. Despite decades of research on superconductivity, the solid state recognition of the superconducting analogue of the diode effect, the dissipationless flow of supercurrent along one direction but not the other, has been not been explored well. In particularly a robust experimental platform shows SDE with well define evidence for the specific mechanism leading to this effect is still lacking. Primary prerequisite of SDE is that the system must have broken both time-reversal and inversion symmetry. By interfacing topology-driven quantum materials (with large SOI) with symmetry-broken systems like exotic superconductors through various films, novel nanostructures including 1D nanowires hold promises to discovery robust SDE. This effect is most robust when the Cooper pair momentum lies at the crossover between weak and strong helical superconducting phase in the close proximity to critical field. This require very fine optimization of spin-orbit coupling, temperature, intrinsic magnetization and magnetic field. One of the primary goal of this project is to identify most suitable superconducting materials platforms which may provide compelling evidence for finite-momentum Cooper-pairing(FMCP) or SDE and understand the underline mechanism. We propose well-controlled experiments to realize robust SDE in Rashba superconducting nanowire with large S-O under in-plane magnetic field. We will synthesize 1D Rashba nanowires of novel metals in which superconductivity can be induced via proximity effect. In the past we have experimentally demonstrated this type of novel heterostructures in the context of Majorana zero modes in TSC. Recently robust SC diode effect has been predicted in both topological insulator and Rashba nanowires. Furthermore, SDE can be significantly enhanced by introducing intrinsic Zeeman field along parallel to the nanowire FM layer. Using gate, we would be able to estimate the parameter space at which the diode efficiency is maximum. Second goal of this project is to establish a materials device platform exhibit strong Josephson diode effect (JDE) in Josephson junctions where two superconducting layer separated by thin barriers made of quantum materials e.g., Dirac/Weyl semimetal. In this task we’ll explore how asymmetry in critical current depends sensitively on direction and magnitude of applied magnetic field. A quantitative characteristic of JJ interference pattern under field will further establish the FMCP emerges from the Zeeman shift of topological surface states. Our approach will not only sharpen the understanding of this novel SDE but it also support to find methods for manipulation to enhance the diode efficiency, crucial to a certain application in the field of Superconducting electronics.