Flux quantized magnetization of superconducting aluminium

The magnetization of a small disc of superconducting aluminium at low magnetic fields is found to show jumps at integer multiples of the fundamental flux quantum. The magnetization is hysteretic depending on whether the field is being increased or reduced. In another experimental measurement of magnetization, the Fraction 10/3 of phi(0) is identified so that the charge e changes to 2e via an intermediate state in which the quasiparticle charge is (3/10)e. Thus the magnetic flux is quantized in fractional as well as integer multiples of hc/2e. (C) 2000 Elsevier Science B.V. All rights reserved.