Width-tuned magnetic order oscillation on zigzag edges of honeycomb nanoribbons

TL;DR

This paper theoretically predicts that the magnetic order on zigzag edges of graphene nanoribbons oscillates between antiferromagnetic and ferromagnetic states as the ribbon width increases, with tunability via magnetic fields, impacting spintronics.

Contribution

It introduces the concept of width-tuned magnetic oscillations in graphene nanoribbons, revealing a new magnetic behavior beyond the known phase transition at 7 nm width.

Findings

Magnetic correlation oscillates with ribbon width between AFM and FM.

Oscillation is tunable with external magnetic fields.

Potential for room-temperature spintronic applications.

Abstract

Quantum confinement and interference often generate exotic properties in nanostructures. One recent highlight is the experimental indication of a magnetic phase transition in zigzag-edged graphene nanoribbons at the critical ribbon width of about 7 nm [G. Z. Magda et al., Nature \textbf{514}, 608 (2014)]. Here we show theoretically that with further increase in the ribbon width, the magnetic correlation of the two edges can exhibit an intriguing oscillatory behavior between antiferromagnetic and ferromagnetic, driven by acquiring the positive coherence between the two edges to lower the free energy. The oscillation effect is readily tunable in applied magnetic fields. These novel properties suggest new experimental manifestation of the edge magnetic orders in graphene nanoribbons, and enhance the hopes of graphene-like spintronic nanodevices functioning at room temperature.