Nanoscale magnetic vortex oscillators
Joo Von Kim (Centre for Nanoscience and Nanotechnology, Université Paris-Saclay, Orsay, France)

The interplay between ferromagnetism at sub-micron dimensions and electric currents gives rise to novel dynamical processes that are not present in bulk systems. An intriguing example involves the magnetic vortex, a topological soliton involving a spiral spin state, which can be driven into self-oscillations by spin torques associated with the flow of spin-polarized currents. By combining such dynamics with the magnetoresistive property of magnetic multilayers, these systems can act as nanoscale electrical oscillators that possess a large frequency tunability in the GHz range. I will discuss recent work involving such vortex oscillations in the nanocontact geometry in which quasi-ballistic motion [1] and chaotic phenomena have been observed [2]. I will also provide some perspectives for chaos-based information processing and neuromorphic computation based on such vortex oscillators.

[1] M. Manfrini et al., Nat. Nanotechnol. 9, 121 (2014).
[2] S. Petit-Watelot et al., Nat. Phys. 8, 682 (2012).