Is Magnetic Flux Quantized in a Toroidal Ferromagnet?

Abstract

Total magnetic flux trapped in a tiny toroidal magnet is measured by an electron holography technique to test predicted flux quantization. The experimental results show that the magnetic flux is quantized neither by $\frac{h}{e}$ units nor by $\frac{h}{2e}$ units. This fact provides further evidence for the existence of the Aharonov-Bohm effect.