Microscopic study of supercurrent diode effect in chiral nanotubes

Abstract: Nonreciprocity of supercurrents may exist when both spatial inversion and time-reversal symmetries are broken, leading to the supercurrent diode effect (SDE). The spatial inversion symmetry may be broken by chiral structures in nanotubes where the SDE is expected when a magnetic flux passes through the tube. While such an effect has been predicted based on a phenomenological theory, a microscopic and quantitative study with a concrete lattice model is missing. Here, we investigate the SDE in chiral nanotubes made of carbon and those made of transition metal dichalcogenides (TMD) with tight-binding models. We obtain the SDE efficiency as a function of the nanotube radius, the chiral angle, the magnetic flux, the temperature, the chemical potential, etc., and find that sign flipping happens in various parameter dependencies. In TMD nanotubes, the SDEs with and without the spin-orbit coupling are compared. We also simulate CNTs made from square lattice materials for comparison and discuss the effects of strains. Besides qualitative consistency with previous phenomenological theory, new features are found and the microscopic origins are clarified.