  Conventional superconductors have vortices carrying integer multiples of
magnetic flux quantum while unconventional ones, with p- or d-wave order
parameter, allow half-integer fluxes. Here we show that mesoscopic size effects
stabilize fractional flux vortices in the thermodynamical ground state of
s-wave two-gap superconductors. The value of these fluxes can be an arbitrary
fraction of flux quantum and can be measured directly from distributions of
magnetic fields on the samples.
