Injection Locking of Antiferromagnetic Oscillators

Antiferromagnetic oscillators are fascinating devices that behave like room temperature Josephson Junction oscillators [1].  These nonlinear auto-oscillators operate through the spin-hall effect, spin transfer torque, and spin pumping.  Antiferromagnetic oscillators (AFMOs) can theoretically produce coherent low range THz signals.  One challenge with AFMOs as THz signal generators is their power due to their nanoscale construction.  A solution to this limitation is the synchronization of many AFMOs to increase aggregate power generation.  To start investigating synchronization coupling options we analyze the behavior of the AFMO in a simple injection locking regime.  In this regime driving currents far above the threshold current are avoided because the AFMO becomes insensitive to anisotropy and thus synchronization cannot be achieved. Even with large damping to avoid hysteretic behavior near the threshold current the pulse train generated is unstable bordering on chaotic like behavior.  Thus injection locking in this manner is not desirable for achieving synchronization of AFMOs.

[1] R. Khymyn, I. Lisenkov, V. Tyberkevych, B. A. Ivanov, & A. Slavin, Scientific Reports 7:43705, DOI: 10.1038/srep43705