Quantitative control of surface pinning in a low-kappa Type II alloy

Quantitative control of surface pinning in the case of In–2% Bi foils was achieved by pressing diffraction gratings into the foil surfaces. The resulting grooves were effective pinners when they were 8.4ξ or wider and ineffective when 4ξ or narrower; the critical Lorentz force for flux flow was consistent with simple static calculations based on the groove geometry. No pinning occurred for flux flow along the grooves. Near Hc2, the strength of pinning decreased linearly with H, and was essentially constant at lower fields. The Jc(H) peak effect was found to depend on pinner spacing.