Detection of discretized single-shell penetration in mesoscopic vortex matter
We investigated configurational changes in mesoscopic vortex matter with less than thousand vortices during flux penetration in freestanding 50 $μ$m diameter disks of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8 +δ}$. High-resolution AC and DC local magnetometry data reveal oscillations in the transmittivity echoed in peaks in the third-harmonics magnetic signal fainting on increasing vortex density. By means of extra experimental evidence and a simple geometrical analysis we show that these features fingerprint the discretized entrance of single-shells of vortices having a shape that mimics the sample edge.
cond-mat.supr-con↗