Probing Phase Coupling Between Two Spin-Torque Nano-Oscillators with an External Source

Li, Yi de Milly, Xavier Abreu Araujo, Flavio [UCL] Klein, Olivier Cros, Vincent Grollier, Julie de Loubens, Grégoire et al.[show all]

Phase coupling between auto-oscillators is central for achieving coherent responses such as synchronization. Here we present an experimental approach to probe it in the case of two dipolarly coupled spin-torque vortex nano-oscillators using an external microwave field. By phase locking one oscillator to the external source, we observe frequency pulling on the second oscillator. From coupled phase equations we show analytically that this frequency pulling results from concerted actions of oscillator-oscillator and sourceoscillator couplings. The analysis allows us to determine the strength and phase shift of coupling between two oscillators, yielding important information for the implementation of large interacting oscillator networks.