Perfect and robust phase-locking of a spin transfer vortex nano-oscillator to an external microwave source

A. Hamadeh (1) , Nicolas Locatelli (2) , V. V. Naletov (1) , Romain Lebrun (2) , G. de Loubens (1) , Julie Grollier (2) , Olivier Klein (1) , V. Cros (2)

1 SPEC - UMR3680 - Service de physique de l'état condensé
2 Laboratoire Albert Fert (ex-UMPhy Unité mixte de physique CNRS/Thales)

We study the synchronization of the auto-oscillation signal generated by the spin transfer driven dynamics of two coupled vortices in a spin-valve nanopillar to an external source. Phase-locking to the microwave field hrf occurs in a range larger than 10% of the oscillator frequency for drive amplitudes of only a few Oersteds. Using synchronization at the double frequency, the generation linewidth is found to decrease by more than five orders of magnitude in the phase-locked regime (down to 1 Hz, limited by the resolution bandwidth of the spectrum analyzer) in comparison to the free running regime (140 kHz). This perfect phase-locking holds for frequency detuning as large as 2 MHz, which proves its robustness. We also analyze how the free running spectral linewidth impacts the main characteristics of the synchronization regime.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

A. Hamadeh, Nicolas Locatelli, V. V. Naletov, Romain Lebrun, G. de Loubens, et al.. Perfect and robust phase-locking of a spin transfer vortex nano-oscillator to an external microwave source. 2013. ⟨hal-00910188⟩