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arXiv · 0707.2964

Magnetism in graphene nano-islands

J. Fernandez-Rossier·J. J. Palacios
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Abstract

We study the magnetic properties of nanometer-sized graphene structures with triangular and hexagonal shapes terminated by zig-zag edges. We discuss how the shape of the island, the imbalance in the number of atoms belonging to the two graphene sublattices, the existence of zero-energy states, and the total and local magnetic moment are intimately related. We consider electronic interactions both in a mean-field approximation of the one-orbital Hubbard model and with density functional calculations. Both descriptions yield values for the ground state total spin, $S$, consistent with Lieb's theorem for bipartite lattices. Triangles have a finite $S$ for all sizes whereas hexagons have S=0 and develop local moments above a critical size of $\approx 1.5$ nm.

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J. Fernandez-Rossier, J. J. Palacios. 2007-10-30. Magnetism in graphene nano-islands. https://doi.org/10.1103/physrevlett.99.177204

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