Seminário de Matéria Condensada - 21/08/2014, 11:00, sala de reuniões do 1P

There is a great interest in the study of magnetic properties of graphene nanoribbons (GNRs) partially motivated proposals for spintronics [1]. Theoretical studies based on the Hubbard mean field approximation [2,3] and the density functional theory [4] predict magnetic ordering at the edges of graphene nanoribbons with zigzag and chiral terminations close to zero doping. This prediction is experimentally supported by the recent STS measurements of a gap in the local density of states close to the edges of chiral nanoribbons [5].

We study the electronic structure and the edge magnetization under ambipolar doping in chiral graphene nanoribbons. We model the GNRs electronic structure using a tight-binding model with nearest and next-nearest hopping terms and account for the electron-electron interactions by including a Hubbard term treated in the mean field approximation. We compare our results to recent scanning tunneling microscopy experiments reporting signatures of magnetic ordering in chiral nanoribbons and provide a new interpretation for the observed peaks in the local density of states.

DOI:10.1103/PhysRevB.89.245444

[1] Y.-W. Son, M. L. Cohen, and S. G. Louie, Nature 444 (2006) 347.

[2] M. Fujita, M. Wakabayashi, K. Nakada, and K. Kusakabe, J. Phys. Soc. Japan 65 (1996) 1920.

[3] O. V. Yazyev, R. B. Capaz, and S. G. Louie, Phys. Rev. B 84 (2011) 115406.

[4] Y.-W. Son, M. L. Cohen, and S. G. Louie, Phys. Rev. Lett. 97 (2006) 216803.

[5] C. Tao, L. Jiao, O. V. Yazyev, Y.-C. Chen, J. Feng, X. Zhang, R. B. Capaz, J. M. Tour, A. Zettl, S. G. Louie, H. Dai, and M. F. Crommie, Nature Phys. 7 (2011) 616.