Injection locking of constriction based spin Hall nano-oscillators

Spin-Hall nano-oscillators (SHNOs) are modern auto-oscillation devices. Their simple geometry allows for an optical characterization by Brillouin-Light-Scattering microscopy at room temperature. Here we report on the observation of auto-oscillations in constriction based SHNOs under the forcing influence of an added alternating current. We show the possibility of injection locking between the applied external signal and the auto-oscillations driven by a direct current. Within the locking range the frequency of the auto-oscillations is forced to the external stimulus. In addition the intensity of the oscillations is increased strongly and the linewidth decreases. Due to the controllability of the auto-oscillations of the magnetization, injection locking can be used to influence the properties of future communication technologies, i.e. based on synchronized constriction based spin Hall nano-oscillators arrays.