Abstract
The authors have measured the magnetic response of 33 individual cold mesoscopic gold rings, one ring at a time. The response of some sufficiently small rings has a component that is periodic in the flux through the ring and is attributed to a persistent current. Its period is close to , and its sign and amplitude vary between rings. The amplitude distribution agrees well with predictions for the typical current in diffusive rings. The temperature dependence of the amplitude, measured for four rings, is also consistent with theory. These results disagree with previous measurements of three individual metal rings that showed a much larger periodic response than expected. The use of a scanning SQUID microscope enabled in situ measurements of the sensor background. A paramagnetic linear susceptibility and a poorly understood anomaly around a zero field are attributed to defect spins.
- Received 24 October 2008
DOI:https://doi.org/10.1103/PhysRevLett.102.136802
©2009 American Physical Society
Viewpoint
Tireless electrons in mesoscopic gold rings
Published 30 March 2009
The surprising prediction that currents can flow forever in small normal metal rings was confirmed almost twenty years ago. Highly precise new experiments find good agreement with theory that was not seen till now.
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