Anomalous Feedback and Negative Domain Wall Resistance

TL;DR

This paper investigates how spin motive-force can lead to negative domain wall resistance in cylindrical nanowires, revealing a feedback regime where the force supports or opposes current flow, depending on material parameters.

Contribution

It introduces the concept of anomalous feedback in spintronics, showing conditions under which negative domain wall resistance occurs due to spin motive-force effects.

Findings

Identification of the anomalous feedback regime at specific torque ratios

Demonstration of negative domain wall resistance in simulations

Analogy between negative resistance and water turbines

Abstract

Magnetic induction can be regarded as a negative feedback effect, where the motive-force opposes the change of magnetic flux that generates the motive-force. In artificial electromagnetics emerging from spintronics, however, this is not necessarily the case. By studying the current-induced domain wall dynamics in a cylindrical nanowire, we show that the spin motive-force exerting on electrons can either oppose or support the applied current that drives the domain wall. The switching into the anomalous feedback regime occurs when the strength of the dissipative torque {\beta} is about twice the value of the Gilbert damping constant {\alpha}. The anomalous feedback manifests as a negative domain wall resistance, which has an analogy with the water turbine.