Domain wall dynamics driven by a localized injection of a spin-polarized current

TL;DR

This paper presents a novel domain wall oscillator driven by localized spin-polarized current injection, demonstrating tunable GHz and sub-GHz oscillations with potential applications in circuit decoupling.

Contribution

It introduces a new oscillator scheme based on domain wall dynamics induced by localized spin-polarized currents, with detailed analysis of two distinct oscillation regimes.

Findings

Achieved over 5 GHz oscillation frequency with linear current dependence.

Identified two dynamical regimes: domain wall propagation and back-and-forth oscillations.

Localized power distribution suitable for circuit decoupling applications.

Abstract

This paper introduces an oscillator scheme based on the oscillations of magnetic domain walls due to spin-polarized currents, where the current is injected perpendicular to the sample plane in a localized part of a nanowire. Depending on the geometrical and physical characteristic of the system, we identify two different dynamical regimes (auto-oscillations) when an out-of-plane external field is applied. The first regime is characterized by nucleation of domain walls (DWs) below the current injection site and the propagation of those up to the end of the nanowire, we also found an oscillation frequency larger than 5GHz with a linear dependence on the applied current density. This simple system can be used as a tuneable steady-state domain wall oscillator. In the second dynamical regime, we observe the nucleation of two DWs which propagate back and forth in the nanowire with a sub-GHz oscillation frequency. The micromagnetic spectral mapping technique shows the spatial distribution of the output power is localized symmetrically in the nanowire. We suggest that this configuration can be used as micromagnetic transformer to decouple electrically two different circuits.