Use of Aharonov-Bohm effect and chirality control in magnetic phase plates for transmission microscopy

Abstract

Initial holographic tests on thin rings of cobalt have demonstrated both onion (O) and vortex (V) states of magnetization, and show that the vortex state provides a uniform phase difference between inside and outside the ring as expected from the Aharonov-Bohm effect. Simple circular rings show a relatively small difference between the in-plane switching fields O→V and V→O and have unpredictable chirality (sense of flux rotation in the vortex mode). Simulations suggest that D-shaped rings provide both predictable chirality and a wider range between switching fields.