Phase locking of vortex based spin transfer oscillators to a microwave current

Abstract

Phase locking experiments on vortex based spin transfer oscillators with an external microwave current are realized. We present clear evidence of synchronization, i.e., phase locking, frequency pulling, as well as fractional synchronization in this system with a minimum peak linewidth of only 3 kHz in the locked state. Large locking ranges are achieved (up to 1/3 of the oscillator frequency) allowing us to demonstrate the simultaneous phase locking of two independent oscillators connected in series with the external source.