IInterfacial Tension and IInterface Delocalization Phase Boundary for Strongly Type-I Superconductors

We analytically determine the iInterface delocalization (or wetting) transition phase boundary in the limit of strongly type-I superconductors. In particular, within Ginzburg-Landau theory we derive an analytic expression for the reduced surface tension, rsc/N, of a type-I superconductor. We find that the truncated expansion rsc/N = 2 ^/2/3- 1.02817 ^/K — 0.13307A: ^/K (where K is the Ginzburg-Landau parameter) is so accurate in the entire type-I regime O ^ K< 1/^/2 that derivation of higher-order terms is unnecessary. We further derive an expression for the wall/superconductor iInterfacial tension which again proves accurate across a broad range of K values. These expansions allow us to locate the low-k iInterface delocalization phase boundary accurately, complementing previous numerical results for the wetting phase diagram.