Nonlinear dynamics of an array of nano spin transfer oscillators

Abstract

The dynamics of a macrospin variable representing homogeneous magnetization of the free layer of a nanospin transfer oscillator (STNO) can be represented by the Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation. This is a generalization of the evolution equation of a ferromagnetic spin system represented by the Heisenberg interaction. STNO is a fascinating nonlinear system exhibiting an interesting bifurcation-chaos scenario depending up on the nature of the applied external magnetic field and the spin current. In order to enhance the microwave power generated by STNOs, recently it has been suggested to consider series and parallel arrays of STNOs with appropriate couplings so that the oscillators get synchronized. We show here the interesting possibility of obtaining synchronization with a common external periodically varying applied magnetic field. We also study the mass synchronization in arrays of STNOs represented by phase oscillators and study the underlying properties.