Spin-Hall nano-oscillator: a micromagnetic study

Experimental studies of bilayer composed by a heavy metal coupled with a thin ferromagnet have opened a route on the development of a more efficient category of spintronic devices based on spin-Hall effect (SHE), where in addition to the switching[1] also self oscillations of magnetization can be excited[2,3]. In a recent experiment[1], those modes remindful of the nonlinear self-localized spin wave-'bullet'. Here, we studied micromagnetically the same experimental framework as in [2] (see Fig.1(a)). We used a Landau-Lifshitz-Gilbert equation which includes a Slonczewski-like torque acting as anti-damping with a polarizer related to the spatial distribution of the spin-current in the Pt layer. The current density distribution has been computed by solving numerically the Ohm law with the electric field computed as the gradient field of the electrostatic potential V. We used Finite Element Method by specifying appropriate boundary conditions.