NONLOCAL PARACONDUCTANCE OF SMALL SUPERCONDUCTING LOOPS

The nonlocal current response to an electric field characteristic of t he superconducting state has been predicted to be observable above the transition temperature T(c) over a length scale set by the correlatio n length for superconducting fluctuations, xi(T). A manifestation of t his effect has been found in a multiterminal measurement of a square s uperconducting loop of characteristic size, L is similar to xi(T). The ratio of the voltages measured by two different sets of probes attach ed at different positions is observed to oscillate as a function of th e flux threading the loop. This nonlocal effect is distinct from analo gous phenomena associated with the coherent transport of electrons in mesoscopic structures.