MAGNETIZATION OF MESOSCOPIC COPPER RINGS - EVIDENCE FOR PERSISTENT CURRENTS

We have measured the low-temperature magnetization response of 107 isolated mesoscopic copper rings to a slowly varying magnetic flux. At sufficiently low temperature, the total magnetization response oscillates as a function of the enclosed magnetic flux on the scale of half of a flux quantum. The amplitude of the oscillatory moment is 1.2×10-15 Am2 and decreases exponentially with increasing temperature on the scale of the correlation energy Ec=hD/(2L)280 mK. This is evidence for a flux-periodic persistent current in each ring of average value 3×10-3eF/L. © 1990 The American Physical Society.