Ferromagnetic Nanorings

Nanoscale magnets exhibit unique magnetic states that can be used as novel data storage devices.  Computer hard drives presently store information in binary bits of “1” and “0” that are encoded in what are effectively little bar magnets with either the north or south pole pointing up.  Magnetic nanorings offer a unique state that has no poles, but instead could store the “1” and “0” as clockwise or counterclockwise magnetic fields in what is called the “vortex” state. 

Control over the chirality (CW or CCW direction) has proven challenging with uniform external fields. The project directly explores the switching of the vortex state by passing a current through the tip of an atomic force microscope.  This current will produce an azimuthal magnetic field that controls the vortex chirality.  Simulations predict that azimuthally applied fields result in interesting states beyond the vortex, generating stable 360 degree domain walls