The project builds upon the recent discovery by consortium members of novel commensurate and chaotic phases in the nanocontact vortex oscillator (Petit-Watelot 2012). The oscillator is based on the self-sustained gyration of a magnetic vortex around a nanocontact, where additional periodic reversals of the vortex core can induce a chaotic state.
Magnetic vortices are spin configurations that arise from competing exchange and dipolar interactions. The vortex comprises moments that circulate in the film plane but culminate at its centre (the “core”) with one of the two orientations perpendicular to this plane (the “polarity”, p). The polarity determines the sense of vortex gyration, i.e., clockwise for p = 1 and anticlockwise for p = –1. Because vortices are topological solitons, they have particle-like properties and their spin structure is determined primarily by the intrinsic properties of the material. Their inherent gyrotropic properties makes them useful for spin-torque nano-oscillators, but they have also been proposed as building blocks for memory (Pigeau 2010, Yu 2011) and logic applications (Jung 2012), since the core polarity can be used as a binary variable.
Further reading
- H. Jung et al., ACS Nano 6, 3712 (2012).
- S. Petit-Watelot et al., Nature Physics 8, 682 (2012).
- B. Pigeau et al., Applied Physics Letters 96, 132506 (2010).
- Y.-S. Yu et al., Applied Physics Letters 98, 052507 (2011).