Stiffness and coherence length measurements of ultra-thin superconductors, and implications for layered superconductors

Based on the London equation, we use a rotor-free vector potential A and current measurements by a SQUID, to determine the superconducting (SC) Pearl length. and coherence length xi(0), of ultra-thin, ring shaped, MoSi films, as a function of thickness d and temperature T. We find that T-c and xi(0) are functions of d and both jump at xi(0) similar to d similar to 5 nm. At base temperature the SC stiffness, defined by 1/lambda(2) = 1/(Lambda d), is an increasing function of T-c. Similar behavior, known as the Uemura plot, exists in bulk layered superconductors, but with doping as an implicit parameter. We also provide the critical exponents of Lambda(T).