Nonlocal paraconductance of small superconducting loops

Field-enhanced superconductivity in disordered wire networks

“…4 These anomalous effects are local in that they diminish rapidly when voltage lead spacings are larger than Q , which is typically about 10 m at these temperatures. 5 In fact, resistance anomalies similar to but smaller than those previously observed [5][6][7][8]3 could be detected in our disordered networks. The effect can be seen in the middle curves of Fig.…”

“…A rich variety of new phenomena can be observed in mesoscopic superconducting structures when the sample dimensions are comparable to or smaller than the superconducting coherence length. 1-9 For example, striking mesoscopic effects involving quantum interference, 1 critical field, 2 and nonlocal 3,4 or anomalous 5-9 magnetotransport have been observed recently in small superconducting loops and wires.…”

“…[5][6][7][8]3 These anomalies appeared as narrow peaks in resistance high on the R(T) transition curve, in some cases exceeding the normal state resistance. At high current densities, the peak anomalies broadened down the resistive transition, producing an apparent reduction in T c .…”

“…This apparently global effect is distinct from but possibly related to the localized nonequilibrium resistance and T c anomalies which were previously observed in small Al microstructures. [5][6][7][8]3 The networks studied consisted of square Al wire grids of 200ϫ100 wires, and were fabricated at the Cornell Nanofabrication facility using electron beam lithography and lift-off techniques. The networks had wire widths of 250 nm and average lattice constant ͑wire spacing͒ aϭ2 m. Positional disorder was added to regular square lattices by random displacement of the nodes r/aϭ(n x ϩ␦ x ,n y ϩ␦ y ) with n x,y integers and ␦ x,y a random number uniformly distributed in the range ͓Ϫ⌬,⌬͔ with ⌬ϭ0, 0.05, 0.10, 0.15 ͑see Fig.…”

Nonlocality and Magnetic Flux Sensitivity of Superconducting Mesoscopic Aluminium Loops

“…Experimental evidence for the nonlocal Little-Parks effect had already been reported in [7]. However, the latter study has been complicated by the presence of strong resistance anomalies at low fields B 5 1 mT.…”