Spin waves in zigzag graphene nanoribbons and the stability of edge ferromagnetism

Abstract

We study the low energy spin excitations of zigzag graphene nanoribbons of varying width. We find their energy dispersion at small wave vector to be dominated by antiferromagnetic correlations between the ribbon's edges, in accrodance with previous calculations. We point out that spin wave lifetimes are very long due to the semi-conducting nature of the electrically neutral nanoribbons. However, application of very modest gate voltages cause a discontinuous transition to a regime of finite spin wave lifetime. By further increasing doping the ferromagnetic alignments along the edge become unstable against transverse spin fluctuations. This makes the experimental detection of ferromagnetism is this class of systems very delicate, and poses a difficult challenge to the possible uses of these nanoribbons as basis for spintronic devices.

New version after major revision

References in corpus (3)

• Energy Gaps in Graphene Nanoribbons
• Half-Metallic Graphene Nanoribbons
• Magnetic Correlations at Graphene Edges

Cited by in corpus (7)

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• Edge magnetization and local density of states in chiral nanoribbons
• Broken-symmetry magnetic phases in two-dimensional triangulene crystals
• Topological edge states of a graphene zigzag nanoribbon with spontaneous edge magnetism
• Interplay between the edge-state magnetism and long-range Coulomb interaction in zigzag graphene nanoribbons: quantum Monte Carlo study
• Applied electric field on zigzag graphene nanoribbons: reduction of spin stiffness and appearance of spiral spin density waves
• Zigzag nanoribbon of gated bilayer hexagonal crystals with spontaneous edge magnetism