Tunable inertia of chiral magnetic domain walls

TL;DR

This paper demonstrates that the acceleration and deceleration times of chiral magnetic domain walls can be independently tuned, enabling more efficient control for memory device applications.

Contribution

It reveals that the inertia of chiral domain walls is tunable through the Dzyaloshinskii-Moriya interaction and spin Hall torque, a novel insight for magnetic memory technology.

Findings

Deceleration time depends on Dzyaloshinskii-Moriya exchange constant.

Acceleration time depends on spin Hall torque.

Decoupling of acceleration and deceleration times enables tunable domain wall inertia.

Abstract

The time it takes to accelerate an object from zero to a given velocity depends on the applied force and the environment. If the force ceases, it takes exactly the same time to completely decelerate. A magnetic domain wall (DW) is a topological object that has been observed to follow this behavior. Here we show that acceleration and deceleration times of chiral Neel walls driven by current are different in a system with low damping and moderate Dzyaloshinskii-Moriya (DM) exchange constant. The time needed to accelerate a DW with current via the spin Hall torque is much faster than the time it needs to decelerate once the current is turned off. The deceleration time is defined by the DM exchange constant whereas the acceleration time depends on the spin Hall torque, enabling tunable inertia of chiral DWs. Such unique feature of chiral DWs can be utilized to move and position DWs with lower current, key to the development of storage class memory devices.