Description
We observe and model the dynamics of a magnetic vortex that circles inside a tunnel junction submitted to a very strong dc current.

Partners
Institut Néel, Grenoble : C. Thirion
Headway Technology, Milpitas, CA-USA

Objectives
Vortex oscillators could be an alternative to the classical macrospin spintronic RF oscillators. Their main advantage is a naturally good spectral purity, the linewith being rather small even in non-optimized samples. Our objective is to properly ascribe the possibility of synchronization of such oscillators.

Latest results
We demonstrated that our vortex oscillator can be synchronized by an external microwave source and that the synchronization is much more efficient when the frequency of the external source is twice the oscillator fundamental frequency. This result can be modelled by considering the system oscillator + source as a parametric oscillator. We now work on frequency modulation either on the oscillator alone or connected to the microwave source.

Related content
“Parametric oscillator based on nonlinear vortex dynamics in low-resistance magnetic tunnel junctions”, S. Y. Martin, N. de Mestier, C. Thirion, C. Hoarau, Y. Conraux, C. Baraduc, and B. Diény, PHYSICAL REVIEW B 84, 144434 (2011)

Patents
“Oscillateur à transfert de spin”, Claire Baraduc, B.Dieny, N.De Mestier, C.Thirion (BD11941)

Figure 1 :

Synchronization of the vortex oscillator