Phase locking of a pair of nano ferromagnetic oscillators on a topological insulator

Abstract

We investigate the magnetization dynamics of a pair of ferromagnetic insulators (FMIs) deposited on the surface of a topological insulator (TI). Due to the nonlinear nature of the underlying physics and intrinsic dynamics, the FMIs can exhibit oscillatory behaviors even under a constant applied voltage. The motion of the surface electrons of the TI, which obeys relativistic quantum mechanics, provides a mechanism of direct coupling between the FMIs. In particular, the spin polarized current of the TI surface electrons can affect the magnetization of the two FMIs, which in turn modulates the electron transport, giving rise to a hybrid relativistic quantum/classical nonlinear dynamical system. We find robust phase and anti-phase locking between the magnetization dynamics. As driving the surface electrons of a TI only requires extremely low power, our finding suggests that nano FMIs coupled by a spin polarized current on the surface of TI have the potential to serve as the fundamental building blocks of unconventional, low-power computing paradigms.