Improved spectral stability in spin transfer nano-oscillators: single vortex versus coupled vortices dynamics

Nicolas Locatelli (1, 2) , Romain Lebrun (1, 2) , Vladimir V. Naletov (1, 2, 3, 4, 5) , Abbass Hamadeh (4) , G. de Loubens (4) , Olivier Klein (4, 5) , Julie Grollier (1, 2) , Vincent Cros (1, 2)

1 UMPhy CNRS/THALES - Unité mixte de physique CNRS/Thales
2 IEF - Institut d'électronique fondamentale
3 KPFU - Kazan State University
4 SPEC - UMR3680 - Service de physique de l'état condensé
5 SPINTEC - SPINtronique et TEchnologie des Composants

We perform a comparative study of spin transfer induced excitation of the gyrotropic motion of a vortex core with either uniform or vortex spin polarizers. The microwave output voltage associated with the vortex dynamics, detected in both cases, displays a strong reduction of phase fluctuations in the case of the vortex polarizer, with a decrease of the peak linewidth by one order of magnitude down to 200kHz at zero field. A thorough study of rf emission features for the different accessible vortex configurations shows that this improvement is related to the excitation of coupled vortex dynamics by spin transfer torques.

Keywords: Spin transfer nano-oscillators; Spin transfer torque; Vortex; Gyrotropic mode; Coupled oscillators; Self- sustained magnetic oscillations; Radio frequency; Microwave

Domains: Physics [physics]

Nicolas Locatelli, Romain Lebrun, Vladimir V. Naletov, Abbass Hamadeh, G. de Loubens, et al.. Improved spectral stability in spin transfer nano-oscillators: single vortex versus coupled vortices dynamics. IEEE Transactions on Magnetics, 2015, ⟨10.1109/TMAG.2015.2414903⟩. ⟨cea-01364272⟩