  It has been proposed that two-band superconductors exhibit a distinct phase
characterized by two correlation lengths, where one is smaller and the other
larger than the magnetic field penetration length. This regime was coined
type-1.5 superconductivity, with a number of unconventional properties, such as
vortex clustering. However a fully microscopic solution for vortex clusters has
remained challenging due to computational complexities beyond quasiclassical
models. In this work, we present numerical solutions obtained in a fully
self-consistent two-band Bogoliubov-de-Gennes model. We show the presence of
discrepant correlation lengths leading to vortex clustering in two-band
superconductors.
