Reversible Steady Domain-Wall Motion Driven by a Direct Current

TL;DR

This paper reveals that in ferrimagnets near the angular momentum compensation point, domain walls can move steadily in either direction under a direct current due to inertial effects, enabling new spintronic functionalities.

Contribution

It demonstrates a novel steady domain-wall motion driven by current in ferrimagnets, caused by inertial dynamics of an internal coordinate, challenging traditional paradigms.

Findings

Domain walls can move steadily in either direction under direct current.

Inertia plays a significant role in nonlinear spin dynamics.

Potential applications include magnetic-field detection and reconfigurable devices.

Abstract

Understanding and manipulating nanoscale domain wall (DW) dynamics is a central topic in magnetism and spintronics for its promising applications in logic and memory devices. In most magnetic systems, inertia affects only transient DW dynamics, while the long-time DW motion is uniquely determined by the magnitude and direction of the applied current. Here we show that this paradigm breaks down in ferrimagnets near the angular momentum compensation point. We demonstrate that a DW can propagate steadily either forward or backward even under a direct current, with the direction controlled solely by the current strength. This anomalous phenomenon originates from the inertial dynamics of an internal DW collective coordinate, which behaves as a massive object evolving in a current-dependent double-well potential. Depending on the driving current, the system relaxes into distinct stable states associated with opposite directions of motion. Our findings reveal an unexpected role of inertia in nonlinear spin dynamics, and enable low-energy spintronic functionalities including sensitive magnetic-field detection and reconfigurable one-port devices.