Stochastic Phase Synchronization of Perpendicularly Magnetized Spin-Torque Oscillators With the Second-Order Uniaxial Anisotropy

Stochastic phase synchronization is investigated for spin-torque oscillators (STOs) with perpendicularly magnetized free layer with the first- and second-order magnetic anisotropy. We numerically calculated the magnetization dynamics for the pair of STOs receiving a dc current with Gaussian noise through common current source, and found that the STOs with the second-order magnetic anisotropy synchronized more effectively than that without the second-order magnetic anisotropy. We analyzed the response of the oscillation phase to a perturbative current, i.e., phase resetting curve, and also found that the STO with the second-order uniaxial anisotropy performs better with stochastic phase synchronization.