DEPINNING TRANSITION OF THE SUPERCONDUCTING NORMAL INTERFACE IN LOW-KAPPA TWINNING-PLANE SUPERCONDUCTORS - INTERFACE POTENTIAL AND INTERFACE DISPLACEMENT/

We study the phase transition in which a superconductor/normal interfa ce depins from a twinning plane in a type-I superconductor. This trans ition is a variant of the recently discovered interface delocalization or ''wetting'' transition in similar materials. We calculate the phas e diagram of the depinning transition as a function of the twinning-pl ane transparency for electrons, and the local enhancement of supercond uctivity. We focus on the limit of strongly type-I materials, kappa -- > 0, in which analytic results can be obtained. We further compute the interface potential V(l) and use that to calculate the displacement p rofile l(y) of the transition zone between a pinned and a depinned sup erconducting/normal interface in the vicinity of a twinning plane. In principle, the interface displacement profile can be probed experiment ally by measuring the location of the jump in the magnetic induction b etween the superconducting and normal phases.