Controlling vortex circularity and polarity

Body: 

Magnetic vortices are of high interest in basic and applied research, e.g. for possible applications in data storage, signal transfer, logic devices, etc. They can be described by the polarity of the central core (with the magnetization pointing "up" or "down") and their circularity (rotational direction of the magnetization around the central core). If it were possible to manipulate both properties independently, two bits could be realized by one such nano-dot with a vortex, similar to our approaches utilizing fourfold nanomagnets.

Researchers have recently shown that the controllability of circularity and polarity depends on the nanostructure height, and that both parameters are controlled simultaneously by applying an in-plane magnetic field. The geometry could be shown to be crucial for the reliability of this approach.

This work shows one possibility to store more than one bit per nanoparticle, potentially paving the way to new magnetic storage systems.

M.-Y. Im et al.
Simultaneous control of magnetic topologies for reconfigurable vortex arrays
NPG Asia Materials 9, e348 (2017)