Matching and hysteresis in vortex lattice mobility in patterned Nb films

V. BEKERIS, C. CHILIOTTE, G. PASQUINI, C.-P LI, F. CASANOVA, J. E. VILLEGAS Y I. K. SCHULLER

Bariloche

Workshop; SUPERFICIES Y MATERIALES NANOESTRUCTURADOS; 2010

CAB CNEA

Matching and hysteresis in vortex lattice mobility in patterned Nb films   The effect in vortex lattice mobility of coexistent weak random and strong periodic pinning is investigated in superconducting Nb films containing either periodic arrays of magnetic nano dots or nano holes. Mobility, observed in ac susceptibility measurements, shows matching anomalies that are known to arise from strong periodic pinning forces.  Novel hysteretical behavior is observed in patterned samples independent of the pinning mechanism.  Matching is observed in a wide temperature range, but hysteresis disappears above a cross over temperature $T \sim  0.75$, where  interstitial random forces become negligible. We describe hysteresis as arising from the coexistence of both weak random and strong periodic pinning.