Dynamics of metastable contact soliton dissipative exchange flows in one-dimensional ferromagnetic channels

TL;DR

This paper explores the complex behavior of contact soliton dissipative exchange flows in ferromagnetic channels, revealing metastable soliton interactions, dynamics, and potential for long-distance spin information transport.

Contribution

It introduces the first detailed numerical analysis of metastable contact solitons in DEFs, highlighting their interactions and dynamic behavior in finite injection regimes.

Findings

Metastable solitons can coexist and be ejected or nucleated within the injection region.

Soliton dynamics depend on the separation of injection regions and spin injection signs.

The study suggests mechanisms for long-distance spin transport via soliton interactions.

Abstract

Dissipative exchange flows (DEFs) are large-amplitude boundary value solutions of ferromagnetic channels. In their low-injection limit, DEFs reduce to spin superfluids. However, in the strong injection limit, nonlinearities dominate close to the injection site and a soliton is formed; this solution has been termed a contact soliton dissipative exchange flow (CS-DEF). Here, we numerically investigate CS-DEF solutions in a moderate injection regime and a finite injection width. We find a solution where two metastable solitons coexist in the injection region. This solution is metastable in the sense that any perturbation to the system will eject one of the solitons out of the injection region. Moreover, soliton dynamics can be excited when two injection regions are separated by a certain distance. We find that the ensuing DEF between the solitons induces a steady-state dynamics in which metastable solitons are continually ejected and nucleated. Furthermore, and depending on the relative signs of the spin injections, the soliton dynamics possess a particular handedness and frequency related to the spin transfer torque delivered by the DEF. Our results provide insights into the transport of spin current by DEFs - where the interaction between DEFs and solitons suggests a mechanism for detaching contact-solitons from the injection boundary. Although this study focuses on the "nonlocal" interaction between solitons, it may lead to the investigation of new mechanisms for inserting solitons in a DEF, e.g., for discrete motion and transport of information over long distances.