Dilation of the giant vortex state in a mesoscopic superconducting loop

We have experimentally investigated the magnetization of a mesoscopic aluminum loop at temperatures well below the superconducting transition temperature $T_c.$ The flux quantization of the superconducting loop was investigated with a $\mu$-Hall magnetometer in magnetic field intensities between $\pm 100\hspace{0.5em}\mathrm{G}.$ The magnetic field intensity periodicity observed in the magnetization measurements is expected to take integer values of the superconducting flux quanta ${\Phi }_0=h/2e.\mathrm{}$ A closer inspection of the periodicity, however, reveals a subflux quantum shift. This fine structure we interpret as a consequence of a so-called giant vortex state nucleating towards either the inner or the outer side of the loop. These findings are in agreement with recent theoretical reports.