MAGNETIC-FLUX-INDUCED CONDUCTANCE STEPS IN MICROWIRES

We predict a new type of steplike fluctuations in the magnetoconductan ce of three-dimensional ballistic microwires. These mesoscopic fluctua tions, which appear on a scale corresponding to a small fraction of th e quantum unit of magnetic flux PHI0=hc/e, are a novel manifestation o f the Aharonov-Bohm effect. The sharp conductance steps are caused by the shift of electronic levels through the Fermi level in a magnetic f ield. The flux-induced steps should be observable in, e.g., submicrome ter Bi whiskers at temperatures of order 0.1 K. Sample-characteristic fluctuations are predicted to appear in fields as low as a few gauss.