Vacancy Effects on Electric and Thermoelectric Properties of Zigzag Silicene Nanoribbons

TL;DR

This study investigates how different vacancy types in zigzag silicene nanoribbons affect their electronic and thermoelectric properties, revealing spin-dependent conductance, magnetoresistance, and potential for spin Seebeck effects.

Contribution

It provides a detailed analysis of vacancy-induced modifications in zigzag silicene nanoribbons using density functional theory and nonequilibrium Green's functions, highlighting new spintronic phenomena.

Findings

Spin-dependent conductance becomes prominent with edge vacancies.

Giant magnetoresistance can be suppressed by asymmetric vacancies.

Room-temperature spin Seebeck effect is predicted in LVs.

Abstract

We study the crystal reconstruction in the presence of monovacancies (MVs), divacancies (DVs) and linear vacancies (LVs) in a zigzag silicene nanoribbon (ZSiNR) with transversal symmetry. Their influence on the electric and thermoelectric properties is assessed by the density functional theory combined with the nonequilibrium Green's functions. In particular, we focus on the spin resolved conductance, magnetoresistance and current-voltage curves. A 5-atom-ring is formed in MVs, a 5-8-5 ring structure in DVs, and a 8-4-8-4 ring structure in LVs. The linear conductance becomes strongly spin dependent when the transversal symmetry is broken by vacancies especially if they are located on the ribbon's edges. The giant magnetoresistance can be smeared by asymmetric vacancies. Single spin negative differential resistance may appear in the presence of LVs and asymmetric MVs or DVs. A strong spin Seebeck effect is expected at room temperature in ZSiNRs with LVs.