Suppression of spin-polarization in graphene nanoribbon by edge defect and impurity

TL;DR

This study uses density functional theory to show that edge defects and impurities in zigzag graphene nanoribbons reduce and eventually eliminate their spin polarization, impacting spintronics applications.

Contribution

It provides a detailed analysis of how edge defects and impurities suppress spin polarization in graphene nanoribbons, highlighting a critical threshold for magnetic stability.

Findings

Spin polarization decreases with defect/impurity concentration.

System becomes non-magnetic at one defect per 10 Å.

Edge states at Fermi energy are reduced or removed.

Abstract

We investigate the effect of edge defects (vacancies) and impurities (substitutional dopants) on the robustness of spin-polarization in graphene nanoribbons (GNRs) with zigzag edges, using density-functional-theory calculations. We found that the stability of the spin state and its magnetic moments decrease continuously with increasing concentration of defects or impurities. The system generally becomes non-magnetic at the concentration of one edge defect (impurity) per 10 angstrom. The spin suppression is shown to be caused by reduction and removal of edge states at the Fermi energy. Our analysis implies an important criterion on the GNR samples for spintronics applications.