Aharonov-Bohm oscillation of resistance observed in a ferromagnetic Fe-Ni nanoring

The magnetoresistance of a ferromagnetic Fe–Ni nanoring with 420 nm in inner diameter and 500 nm in outer diameter was measured at very low temperatures below 100 mK. When a magnetic field is applied to the ring, the magnetoresistance exhibits oscillations whose period varies according to the field direction. This demonstrates the Aharonov–Bohm effect of the conduction electrons in the ferromagnetic nanoring. The amplitude of the oscillations can be regarded from the viewpoint of competition between the system size and the phase coherence length of the conduction electrons.