Current-Driven Domain Wall Depinning and Propagation in Notched Nanowires

TL;DR

This paper demonstrates that notches in nanowires facilitate domain wall depinning and propagation at lower current densities, revealing complex interactions and implications for spintronic device design.

Contribution

It uncovers that notches lower the depinning current and enable sustainable domain wall propagation at sub-threshold currents, advancing understanding of current-driven domain wall dynamics.

Findings

Notches reduce the depinning current density.

Domain wall displacement is insensitive to notch geometry.

Sub-threshold currents can sustain domain wall propagation.

Abstract

Adiabatic spin transfer torque induced domain wall (DW) depinning from a notch and DW propagation in a nanowire with a series of notches is investigated. Surprisingly, notches help a current to depin a DW and make a DW easier to propagate along a wire. Following fascinating results on DW dynamics are found. 1) The depinning current density of a DW in a notch is substantially lower than the intrinsic threshold value below which a sustainable DW propagation doesn't exist in a homogeneous wire. 2) The DW displacement from a notch is insensitive to notch geometry and current density when it is between the depinning and the intrinsic threshold current density. 3) A current density below the intrinsic threshold value can induce a sustainable DW propagation along notched nanowires. These findings not only reveal interesting and complicated interaction between a current and a DW, but also have profound implications in our current understanding of current-driven DW dynamics as well as in the design of spintronic devices.