Study of vortex state in mesoscopic superconductors by Hall magnetometry

The vortex states in mesoscopic superconductors with the size comparable to the coherence length differ from those in macroscopic superconductors. The change in the vortex configuration is reflected in the profile of stray magnetic field emanating from the superconductor, which can be detected by a local field probe. In the present study, a mesoscopic Hall cross structure fabricated from GaAs/AlGaAs two-dimensional electron gas (2DEG) was used as the local field probe. The mesoscopic superconductor sample (an Al square with a hole at each corner) was placed on top of the 2DEG Hall probe, which had several arms around the Al square. Because these arms were smaller than the square, we could detect the change of the local field distribution from the change of Hall resistance obtained from different sets of current/voltage probes. The changes furnish relevant information on the vortex configuration.