Magnetic and thermal characteristics of armchair graphene nanoribbons in the two-band Harrison model

In this study, within a two-band tight-binding Harrison Hamiltonian and the Green's function approach, the influences of both localized σ and delocalized π electrons on the Pauli paramagnetic susceptibility, heat capacity and density of states of armchair graphene nanoribbons with different widths are investigated. Temperature dependence of the paramagnetic susceptibility and electronic heat capacity are compared for s and p orbitals of every width. In the density of states, an extension in the bandwidth and the extra number of Van-Hove singularities are observed. More importantly, a paramagnetic behavior associated with the π electrons could take place. Finally, a Schottky anomaly for the heat capacity is reported. Overall, in this paper, it was observed that both the σ and the π electrons contribute significantly to the aforementioned quantities.