  The ground state with vorticity larger than one in mesoscopic superconductors
in applied magnetic field may manifest as a `giant'-vortex, where all vortices
coalesce into a single singularity of the order parameter. Such a multi-quanta
vortex may split into individual vortices (and vice versa) as a function of
e.g. applied current, magnetic field or temperature. Here we show that such
transitions can be identified by heat-capacity measurements, as the formation
or splitting of a giant-vortex results in a clear jump in measured heat
capacity vs. external drive. We attribute this phenomenon to an abrupt change
in the density of states of the quasiparticle excitations in the vortex
core(s), and further link it to a sharp change of the magnetic susceptibility
at the transition - proving that formation of a giant-vortex can also be
detected by conventional magnetometry.
