Modulation of Individual and Mutually Synchronized Nanocontact-Based Spin Torque Oscillators

We study current modulation of spin torque oscillators (STOs) based on single and double nano-contacts. For single nano-contact devices, we show modulation for a carrier frequency of 19-40 GHz and modulation frequencies from 50 MHz to 1 GHz. We show that the behavior of modulation and the asymmetry in the power of the modulation sidebands can be very well modeled, and predicted, using nonlinear frequency and amplitude modulation (NFAM) calculations based on the free-running STO parameters. Modulation of synchronized double nano-contact STOs is equally well modeled by NFAM theory and demonstrates the feasibility of communication applications based on arrays of synchronized STOs.