High domain wall velocities due to spin currents perpendicular to the plane

TL;DR

This paper demonstrates that spin valves with perpendicular spin currents can achieve significantly higher domain wall velocities than those with in-plane currents, with velocities reaching up to 640 m/s.

Contribution

The study numerically analyzes domain wall dynamics driven by perpendicular spin currents, revealing velocities much higher than previous in-plane current-driven cases.

Findings

High domain wall velocities of 50 m/s with planar polarizer

High domain wall velocities of 640 m/s with perpendicular polarizer

Perpendicular spin currents produce larger spin torques leading to faster DW motion

Abstract

We consider long and narrow spin valves composed of a first magnetic layer with a single domain wall (DW), a normal metal spacer and a second magnetic layer that is a planar or a perpendicular polarizer. For these structures, we study numerically DW dynamics taking into account the spin torques due to the perpendicular spin currents. We obtain high DW velocities: 50 m/s for planar polarizer and 640 m/s for perpendicular polarizer for J = 5*10^6 A/cm^2. These values are much larger than those predicted and observed for DW motion due to the in-plane spin currents. The ratio of the magnitudes of the torques, which generate the DW motion in the respective cases, is responsible for these large differences.