Spin states of zigzag-edged Mobius graphene nanoribbons from first principles

TL;DR

This study uses first-principles calculations to explore how the unique Mobius topology influences the magnetic states of zigzag-edged graphene nanoribbons, revealing ground states with non-zero magnetization and edge spin domain formations.

Contribution

It provides the first detailed analysis of spin states in Mobius graphene nanoribbons, highlighting the impact of topology on magnetic properties compared to traditional nanoribbons.

Findings

Mobius topology leads to non-zero total magnetization in ZMGNRs.

Wider ZMGNRs exhibit increased magnetization with length.

Edge spins form domains with frustrated boundary spins.

Abstract

Mobius graphene nanoribbons have only one edge topologically. How the magnetic structures, previously associated with the two edges of zigzag-edged flat nanoribbons or cyclic nanorings, would change for their Mobius counterparts is an intriguing question. Using spin-polarized density functional theory, we shed light on this question. We examine spin states of zigzag-edged Mobius graphene nanoribbons (ZMGNRs) with different widths and lengths. We find a triplet ground state for a Mobius cyclacene, while the corresponding two-edged cyclacene has an open-shell singlet ground state. For wider ZMGNRs, the total magnetization of the ground state is found to increase with the ribbon length. For example, a quintet ground state is found for a ZMGNR. Local magnetic moments on the edge carbon atoms form domains of majority and minor spins along the edge. Spins at the domain boundaries are found to be frustrated. Our findings show that the Mobius topology (i.e., only one edge) causes ZMGNRs to favor one spin over the other, leading to a ground state with non-zero total magnetization.