Spin negative differential resistance in edge doped zigzag graphene nanoribbons

TL;DR

This study investigates spin-dependent transport and negative differential resistance in edge-doped zigzag graphene nanoribbons, revealing how dopant type, geometry, and width influence spin polarization and electronic behavior for potential spintronics applications.

Contribution

It systematically analyzes the effects of edge doping, dopant type, and geometrical symmetry on spin transport and NDR in ZGNRs using density functional theory and non-equilibrium Green's functions.

Findings

Spin NDR occurs only in even-width ZGNRs doped with group III elements.

Odd-width ZGNRs do not exhibit clear spin NDR.

The bias range of spin NDR increases with ZGNR width.

Abstract

The nonlinear spin-dependent transport properties in zigzag graphene nanoribbons (ZGNRs) edge doped by an atom of group III and V elements are studied systematically using density functional theory combined with non-equilibrium Greens functions. The dopant type, acceptor or donor, and the geometrical symmetry, odd or even, are found critical in determining the spin polarization of the current and the current-voltage characteristics. For ZGNRs substitutionally doped on the lower-side edge, the down (up) spin current dominates in odd-(even-)width ZGNRs under a bias voltage around 1V. Remarkably, in even-width ZGNRs, doped by group III elements (B and Al), negative differential resistance (NDR) occurs only for down spins. The bias range of the spin NDR increases with the width of ZGNRs. The clear spin NDR is not observed in any odd-width ZGNRs nor in even-width ZGNRs doped by group V elements (N, and P). This peculiar spin NDR of edge doped ZGNRs suggests potential applications in spintronics.