Synchronization of parallel-connected spin-transfer oscillators via magnetic feedback

We propose an array of spin-transfer oscillators (STOs) to be parallel-connected and synchronized via magnetic feedback. Based on numerically solving the Landau-Lifshitz-Gilbert-Slonczewski equation and theoretically analyzing the Kuramoto model, the cooperative dynamics of these STOs is studied in detail and the optimal orientation of magnetic feedback is determined. It is found that a large locked bandwidth can be obtained by simply increasing the number of coupled STOs and modulating the total phase shift of feedback signals. Specifically, for ten parallel-connected STOs, the locked bandwidth can be 12 times larger than that obtained from the serially connected STOs. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3692762]