Nonlocal response and surface-barrier-induced rectification in Hall-shaped mesoscopic superconductors

Abstract

Nonlocal response in Hall-shaped superconductors is studied using the time-dependent Ginzburg-Landau equations. Applying current in one pair of contacts leads to a voltage drop in another pair of contacts situated at a distance much larger than the coherence length. This effect is a consequence of the long range correlations in a one-dimensional vortex lattice squeezed in a narrow channel by screening currents. The discrete change in the number of vortices in the channel with applied magnetic field leads to a nonlocal response which is a nonmonotonous function of the magnetic field. For specific configurations of the Hall-shaped superconductor we found a rectifying effect.

Evidence of vortex jamming in Abrikosov vortex flux flow regime

“…Vortices are channelled into a constriction on the order of few vortex cores wide 15 . We show that the vortex mobility is asymmetric with respect to the direction of motion of the vortices, as observed by the nonlocal voltage in Nb bridges, and discussed theoretically by Vodolazov et al 12 . The experimental evidence of granular-like behavior of vortex matter that we show in this paper should initiate wider application of theoretical concepts developed in the physics of granular materials to the behavior of superconducting vortices.…”

Superconducting vortex pinning with artificial magnetic nanostructures

“…In addition to the above-described system, vortex ratchets have been experimentally realized in films with asymmetric arrangements of ''antidots'' [161,162], square arrays of Cu nanotriangles [163], Josephson junctions arrays [164], superconducting constrictions (induced by surface-barrier effects) [165], asymmetric pinning produced with ion irradiation [166], magnetized strips [167] or spacing-graded arrays of pinning centers [168], in asymmetric-shaped mesoscopic superconductors [169], and in films with arrays of magnetic dipoles [170,171]. The phenomenology observed in these systems is very rich.…”

“…As reviewed in Section 5.1, certain types of asymmetric pinning potentials are able to rectify AC driving forces, leading to a new type of controlled vortex motion in which the vortex lattice acquires a net velocity driven by an unbiased (zero time-averaged) alternate drive [35,36,162,[164][165][166]172,179,[188][189][190]. This socalled ''ratchet effect'' offers a unique system in which nonequilibrium properties of the vortex lattice can be investigated.…”

“…A worthwhile avenue of research is the preparation of ratchet potentials induced by ''surface barriers'' [165,189], as opposed to inducing them with asymmetric pinning centers distributed within the bulk of superconductors. It is well known that the entrance/exit of vortices in a superconducting film is governed by different surface barriers (such as Bean-Livingston or geometric barriers [192]).…”

Predicted field-dependent increase of critical currents in asymmetric superconducting nanocircuits

“…8,9 Theoretical studies have examined how the quality of the surface can alter the Bean-Livingston barrier in bulk superconductors in parallel fields. [10][11][12][13] Several experimental and theoretical studies of thin films [14][15][16][17] have examined the role of edge pinning and found vortex nucleation preferentially occurring at defects along the edge or at sharp corners where current crowding [18][19][20] occurs. An increase or decrease in the critical current (a diode effect) has been found experimentally to depend upon the sign of a magnetic field parallel to the surface of a superconducting strip with a magnetized magnetic strip on top, an effect the authors explained chiefly in terms of an edge-barrier effect.…”