Microscopic structure of multiquantum vortices in superconductors

Abstract

Superconducting quasiparticle excitation spectra are computed for m times quantized axisymmetric flux lines in s-wave superconductors, using the self-consistent Bogoliubov–de Gennes approach. We find that there occur m branches of bound-state excitations in the electronic spectrum as a function of the quasiparticle angular momentum. At low temperatures, this spectral structure leads to a layered supercurrent distribution which, unlike the Ginzburg–Landau form, displays m extrema as a function of radial distance from the vortex axis; also, owing to these bound states, the STM tunneling conductance of an m times quantized flux line is predicted to display m rows of peaks.