Enhancement of Persistent Currents due to Confinement in Metallic Samples

Abstract

Confinement and surface roughness (SR) effects on the magnitude of the persistent current are analyzed for ballistic bidimensional metallic samples. Depending on the particular geometry, localized border states can show up at half-filling. These border states contribute coherently to the persistent current and its magnitude is enhanced with respect to their value in the absence of confinement. A linear scaling of the typical current I(typ) with the number of conduction channels M is obtained. This result is robust with respect to changes in the relevant lengths of the samples and to the SR. Possible links of our results to experiments are also discussed.

Diamagnetic persistent currents for electrons in ballistic billiards subject to a point flux

“…Much experimental work has been carried out on ensembles of rings/quantum dots 6,7 in a flux as well as on single metallic 8,9,10,11,12 or semiconductor quantum dots/rings 13,14,15,16 . The subject has a long theoretical history as well 17,18,19,20,21,22,23,24,25,26 .…”

Persistent currents in diffusive metallic cavities: Large values and anomalous scaling with disorder

“…11 In a recent work we have shown that by effect of confinement, large values of PC's can arise in the half filling regime for clean metallic cavities of different shapes. 12 In this paper we address the effect of bulk disorder in confined metallic systems threaded by a magnetic flux. We are mainly concerned with the interplay between confinement and disorder effects and in particular with the sensitivity of the persistent current to the strength of disorder w. Our main result is that even deep in the diffusive regime large values of persistent currents can still be obtained for a wide variety of sample shapes.…”

“…12, with the additional inclusion of diagonal disorder. Once the profile of the sample is defined, the on-site energies are taken randomly distributed in the interval ͓Ϫw/2,w/2͔.…”

“…Due to the absence of crossings between occupied and empty levels close to half filling, I ty p increases monotonically with the number of particles. 12 The PL, Fig. 1͑d͒, corresponds to a generic geometry where the mentioned symmetry condition is not fulfilled.…”

Level and eigenfunction statistics in billiards with surface disorder

“…A treatment of Ref. 28, which models surface disorder by cutting off the boundary sites by confining potential and eventually proceeds with numerical evaluation of persistent currents, seems to describe a similar physical situation.…”