Dynamics of spin spirals in a voltage biased 1D conductor

TL;DR

This paper investigates how voltage bias influences the dynamical behavior of spin spirals in a one-dimensional magnetic system, revealing transitions from rigid rotation to chaos and implications for spin transport.

Contribution

It introduces a theoretical framework for understanding voltage-induced dynamical regimes of spin spirals, including chaotic behavior and transport signatures, in 1D magnetic conductors.

Findings

Rigidly rotating non-coplanar structure at low bias

Transition to quasi-periodic and chaotic regimes with increasing bias

Spin polarization transfer in the rotating state

Abstract

We analyze the fate of spiral order in a one-dimensional system of localized magnetic moments coupled to itinerant electrons under a voltage bias. Within an adiabatic approximation for the dynamics of the localized spins, and in the presence of a phenomenological damping term, we demonstrate the occurrence of various dynamical regimes: At small bias a rigidly rotating non-coplanar magnetic structure is realized which, by increasing the applied voltage, transitions to a quasi-periodic and, finally, fully chaotic evolution. These phases can be identified by transport measurements. In particular, the rigidly rotating state results in an average transfer of spin polarization. We analyze in detail the dependence of the rotation axis and frequency on system's parameters and show that the spin dynamics slows down in the thermodynamic limit, when a static conical state persists to arbitrarily long times. Our results suggest the possibility of discovering non-trivial dynamics in other symmetry-broken quantum states under bias.