Large magnetoresistance from long-range interface coupling in armchair graphene nanoribbon junctions

TL;DR

This paper demonstrates a spin valve using armchair graphene nanoribbons that achieves up to 900% magnetoresistance by exploiting long-range coupling of edge states, promising advances in graphene-based spintronics.

Contribution

It introduces a novel AGNR-based spin valve architecture that leverages long-range edge state coupling to produce large magnetoresistance effects.

Findings

Achieved magnetoresistance up to 900%.

Long-range extension of edge states enables perfect transmission.

Magnetic field can switch the transmission channel on and off.

Abstract

In recent years, bottom-up synthesis procedures have achieved significant advancements in atomically-controlled growth of several-nanometer-long graphene nanoribbons with armchair-shaped edges (AGNRs). This greatly encourages us to explore the potential of such well-defined AGNRs in electronics and spintronics. Here, we propose an AGNR based spin valve architecture that induces a large magnetoresistance up to 900%. We find that, when an AGNR is connected perpendicularly to zigzag-shaped edges, the AGNR allows for long-range extension of the otherwise localized edge state. The huge magnetoresistance is a direct consequence of the coupling of two such extended states from both ends of the AGNR, which forms a perfect transmission channel. By tuning the coupling between these two spin-polarized states with a magnetic field, the channel can be destroyed, leading to an abrupt drop in electron transmission.