Electronic transport through domain walls in ferromagnetic nanowires: Co-existence of adiabatic and non-adiabatic spin dynamics

TL;DR

This paper investigates how domain walls in ferromagnetic nanowires influence electronic transport, revealing a coexistence of adiabatic and non-adiabatic spin dynamics that depend on the domain wall length and electron energy.

Contribution

It provides a numerical analysis of spin-dependent transport across various domain wall shapes, highlighting the coexistence of different spin dynamic regimes in ferromagnetic nanowires.

Findings

Low-energy electrons undergo adiabatic spin following.

High-energy electrons are largely unaffected by the domain wall.

The shape of the domain wall has minimal impact on qualitative behavior.

Abstract

We study the effect of a domain wall on the electronic transport in ferromagnetic quantum wires. Due to the transverse confinement, conduction channels arise. In the presence of a domain wall, spin up and spin down electrons in these channels become coupled. For very short domain walls or at high longitudinal kinetic energy, this coupling is weak, leads to very few spin flips, and a perturbative treatment is possible. For very long domain wall structures, the spin follows adiabatically the local magnetization orientation, suppressing the effect of the domain wall on the total transmission, but reversing the spin of the electrons. In the intermediate regime, we numerically investigate the spin-dependent transport behavior for different shapes of the domain wall. We find that the knowledge of the precise shape of the domain wall is not crucial for determining the qualitative behavior. For parameters appropriate for experiments, electrons with low longitudinal energy are transmitted adiabatically while the electrons at high longitudinal energy are essentially unaffected by the domain wall. Taking this co-existence of different regimes into account is important for the understanding of recent experiments.