Edge magnetization and local density of states in chiral graphene nanoribbons

Abstract

We study the edge magnetization and the local density of states of chiral graphene nanoribbons using a π-orbital Hubbard model in the mean-field approximation. We show that the inclusion of a realistic next-nearest hopping term in the tight-binding Hamiltonian changes the graphene nanoribbons band structure significantly and affects its magnetic properties. We study the behavior of the edge magnetization upon departing from half filling as a function of the nanoribbon chirality and width. We find that the edge magnetization depends very weakly in the nanoribbon width, regardless of chirality as long as the ribbon is sufficiently wide. We compare our results to recent scanning tunneling microscopy experiments reporting signatures of magnetic ordering in chiral nanoribbons and provide an interpretation for the observed peaks in the local density of states, that does not depend on the antiferromagnetic interedge interaction.

Bottom-Up Fabrication of Atomically Precise Graphene Nanoribbons

“…As described in the previous section, the edge state magnetization in zigzag and chiral GNRs drives the opening of a band gap  0 and an additionally split resonance  1 related to the inter-edge and intra-edge magnetic coupling, respectively ( Fig. 10) [ 69,74,76]. Thus, as expected from their respective nature,  1 hardly varies with the ribbon´s width.…”

Braiding of edge states in narrow zigzag graphene nanoribbons: Effects of third-neighbor hopping on transport and magnetic properties

“…Using standard Mulliken population analysis in the inset (b), we show the magnetic moment m(µ B ) in Bohr magneton units associated to the edge atoms; it decreases as the number of zigzag lines does and attains its min-imum value for N = 2, where the competition occurs between NM and AF configurations, but it does not vanish as we expect from the non-satisfaction of the previously discussed Stoner criterion. On the other hand, a recent work [16], which studied ZGNRs employing a TB Hubbard model and considering N N and N 2 hopping, obtained a vanishing magnetization for low N, even satisfying the Stoner criterion.…”

Exact diagonalization study for nanographene: Modulation of charge and spin, magnetic phase diagram, and thermodynamics

“…There is a significant volume of work especially on nanoribbons using Hubbard and Hubbard-like models [10][11][12] to explore the effect of correlations. The strength of Coulomb interactions in graphene has been clarified recently.…”