Persistent Currents in Normal Metal Rings

Abstract

Normally Persistent In superconductors, currents are expected to flow persistently without dissipation. Quantum mechanics predicts that such persistent currents should also exist in normal mesoscopic metal rings. However, the predicted effect is small, which has made the detection of these currents difficult. Bleszynski-Jayich et al. (p. 272 ; see the Perspective by Birge ) have developed a sensitive technique based on a nanomechanical resonator. An array of aluminum rings on the end of a resonator was fabricated to monitor the shift in frequency of the resonator as the rings were threaded with quanta of magnetic-field flux, setting up currents in the rings. In agreement with a theoretical scenario put forward over a decade ago, the results could be described with a model based on non-interacting electrons.