Dr. Ania Bleszynski-Jayich
Yale University

 

Measurements of persistent currents in normal metal rings using a
micromechanical magnetometer

A striking manifestation of quantum mechanics is the existence of a dissipationless current in a non-superconducting metal ring. This persistent current is a micron scale analog of the orbital angular momentum of electrons in atoms. Since its prediction over 20 years a handful of experiments have reported a persistent current, with many of the results in disagreement with theory and with each other. The small size of the current and the necessity of measuring it through its associated magnetic moment have left the controversy surrounding persistent currents unresolved.

I present measurements of persistent currents in normal metal rings using a cantilever based torsional magnetometer we developed, which is more sensitive and less invasive than the detectors used in the past, primarily SQUID’s. Our results provide the clearest picture to date of the temperature, ring size, array size, and magnetic field dependence of the persistent current.