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Sensory-organ-like response determines the magnetism of zigzag-edged honeycomb nanoribbons

Bhowmick, Somnath and Medhi, Amal and Shenoy, Vijay B (2013) Sensory-organ-like response determines the magnetism of zigzag-edged honeycomb nanoribbons. In: PHYSICAL REVIEW B, 87 (8).

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Official URL: http://dx.doi.org/10.1103/PhysRevB.87.085412


We present an analytical effective theory for the magnetic phase diagram for zigzag-edge terminated honeycomb nanoribbons described by a Hubbard model with an interaction parameter U. We show that the edge magnetic moment varies as ln U and uncover its dependence on the width W of the ribbon. The physics of this owes its origin to the sensory-organ-like response of the nanoribbons, demonstrating that considerations beyond the usual Stoner-Landau theory are necessary to understand the magnetism of these systems. A first-order magnetic transition from an antiparallel orientation of the moments on opposite edges to a parallel orientation occurs upon doping with holes or electrons. The critical doping for this transition is shown to depend inversely on the width of the ribbon. Using variational Monte Carlo calculations, we show that magnetism is robust to fluctuations. Additionally, we show that the magnetic phase diagram is generic to zigzag-edge terminated nanostructures such as nanodots. Furthermore, we perform first-principles modeling to show how such magnetic transitions can be realized in substituted graphene nanoribbons. DOI: 10.1103/PhysRevB.87.085412

Item Type: Journal Article
Additional Information: Copyright for this article belongs to AMER PHYSICAL SOC, USA
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Division of Physical & Mathematical Sciences > Physics
Date Deposited: 11 Mar 2013 11:28
Last Modified: 11 Mar 2013 11:28
URI: http://eprints.iisc.ac.in/id/eprint/45990

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