Journal of Low Temperature Physics 103, 71 (1996)

M. Ziese, P. Esquinazi, S. Knappe and H. Koch

Abstract

The properties of the flux line lattice in the thin strands of superconducting niobium wire networks with thickness and width comparable to the penetration depth are investigated in the limit of very few flux lines. An angle dependent upper critical field is observed that is consistent with the existence of surface superconductivity. Our results indicate the existence of a flux line lattice in the complete field range B_c| < B < B_c|| ~ 1.4 B_c2. The flux line lattice undergoes a dimensional crossover when the transversal correlation 1ength R_c is of the order of the strand width. The field dependence of the Labusch parameter due to surface pinning is determined and compared to a model for surface pinning by Bean-Livingston barriers.