Effects of Domain Wall on Electronic Transport Properties in Mesoscopic Wire of Metallic Ferromagnets

TL;DR

This paper investigates how domain walls influence electronic transport in ferromagnetic wires, revealing negligible effects in bulk but significant impacts in nanocontacts and disordered systems, including quantum corrections and conductance changes.

Contribution

It provides a theoretical analysis of the electron-wall interaction effects on conductivity, incorporating both classical and quantum effects, especially in nanoscale and disordered ferromagnetic wires.

Findings

Classical conductivity is negligibly affected in bulk due to wall thickness.

Quantum corrections can decrease resistivity by dephasing electrons.

Wall motion can induce measurable conductance changes.

Abstract

We study the effect of the domain wall on electronic transport properties in wire of ferromagnetic 3$d$ transition metals based on the linear response theory. We considered the exchange interaction between the conduction electron and the magnetization, taking into account the scattering by impurities as well. The effective electron-wall interaction is derived by use of a local gauge transformation in the spin space. This interaction is treated perturbatively to the second order. The conductivity contribution within the classical (Boltzmann) transport theory turns out to be negligiblly small in bulk magnets, due to a large thickness of the wall compared with the fermi wavelength. It can be, however, significant in ballistic nanocontacts, as indicated in recent experiments. We also discuss the quantum correction in disordered case where the quantum coherence among electrons becomes important. In such case of weak localization the wall can contribute to a decrease of resistivity by causing dephasing. At lower temperature this effect grows and can win over the classical contribution, in particular in wire of diameter $L_{\perp}\lesssim \ell_{\phi}$, $\ell_{\phi}$ being the inelastic diffusion length. Conductance change of the quantum origin caused by the motion of the wall is also discussed.