Magnetic Correlations in Short and Narrow Graphene Armchair Nanoribbons

TL;DR

This paper explores magnetic edge states in narrow graphene armchair nanoribbons, proposing experiments to detect their nonlinear magnetic responses and providing effective theories for understanding these phenomena.

Contribution

It introduces a theoretical framework and experimental proposals for probing magnetic correlations in graphene nanoribbons, emphasizing the simplicity and control of the setup.

Findings

Nonlinear magnetic responses predicted for edge states.

Effective low-energy theories facilitate analysis of magnetic correlations.

Proposed experiments can detect entangled spin pairs at ribbon ends.

Abstract

Electronic states at the ends of a narrow armchair nanoribbon give rise to a pair of non-locally entangled spins. We propose two experiments to probe these magnetic states, based on magnetometry and tunneling spectroscopy, in which correlation effects lead to a striking, nonlinear response to external magnetic fields. On the basis of low-energy theories that we derive here, it is remarkably simple to assess these nonlinear signatures for magnetic edge states. The effective theories are especially suitable in parameter regimes where other methods such as quantum Monte-Carlo simulations are exceedingly difficult due to exponentially small energy scales. The armchair ribbon setup discussed here provides a promisingly well-controlled (both experimentally and theoretically) environment for studying the principles behind edge magnetism in graphene-based nano-structures.