Spin-Torque-Induced Rotational Dynamics of a Magnetic Vortex Dipole

TL;DR

This paper investigates the spin-torque-driven rotational dynamics of magnetic vortex dipoles in thin-film nanopillars, demonstrating a new type of microwave nano-oscillator with potential technological applications.

Contribution

It introduces a novel spintronic nano-oscillator based on vortex dipole dynamics driven by localized spin torque, supported by experimental and numerical evidence.

Findings

Large amplitude microwave emission at zero magnetic field

Frequency below uniform ferromagnetic resonance

Steady-state vortex dipole rotation driven by localized spin torque

Abstract

We study, both experimentally and by numerical modeling, the magnetic dynamics that can be excited in a magnetic thin-film nanopillar device using the spin torque from a spatially localized current injected via a 10s-of-nm-diameter aperture. The current-driven magnetic dynamics can produce large amplitude microwave emission at zero magnetic field, with a frequency well below that of the uniform ferromagnetic resonance mode. Micromagnetic simulations indicate that the physical origin of this efficient microwave nano-oscillator is the nucleation and subsequent steady-state rotational dynamics of a magnetic vortex dipole driven by the localized spin torque. These results show this novel implementation of a spintronic nano-oscillator is a promising candidate for microwave technology applications.