Ballistic Conductance and Magnetism in Short Tip-Suspended Ni Nanowires

TL;DR

This study investigates the electronic, magnetic, and conductance properties of short nickel nanowires suspended between ferromagnetic leads using density-functional theory, revealing spin-dependent conductance characteristics and the effects of structural relaxation.

Contribution

It provides a detailed first-principles analysis of spin-dependent ballistic conductance and magnetic properties in Ni nanowires, highlighting the contributions of different electronic states.

Findings

Total conductance around 1.6 G_0 matches experimental peaks.

Majority spin s-like channel contributes about 0.5 G_0.

Minority spin conductance is approximately 1.1 G_0 with d-state contributions.

Abstract

Electronic and transport properties of a short Ni nanowire suspended between two semi-infinite ferromagnetic Ni leads are explored in the framework of density-functional theory. The spin-dependent ballistic conductance of the nanowire is calculated using a scattering-based approach and the Landauer-Buttiker formula. The total calculated conductance in units of $G_0 = 2e^2/h$ is around 1.6, in fairly good agreement with the broad peak observed around 1.5 for the last conductance step in break junctions. Separating contributions from different spins, we find nearly 0.5 $G_0$ from the majority spin $s$-like channel, whereas the remaining minority spin conductance of 1.1 $G_0$ contains significant contributions from several $d$ states, but much less than 0.5 $G_0$ from $s$ states. The influence of the structural relaxation on the magnetic properties and the ballistic conductance of the nanowire is also studied.