VietNam 2013 

IXth Rencontres du Vietnam
Quy-Nhon, August 4-10, 2013


 Nanophysics: from fundamentals to applications

(the return)


Friday 9

› 9:00 - 9:30 (30min)
Electronic properties in Moiré superlattice in graphene
Mikito Koshino  1@  , Pilkyung Moon  2@  
1 : Tohoku University
Aoba 6-3, Sendai 980-8578, Japan -  Japan
2 : School of Computational Sciences, Korea Institute for Advanced Study (KIAS)
85 Hoegiro, Dongdaemun, Seoul 130-722, Republic of Korea -  South Korea

We theoretically investigate the electronic properties of twisted bilayer graphene (TBG). TBG is a graphene bilayer system in which two graphene layers are rotationally stacked with an arbitrary orientation. The misoriented lattice structure of the two graphene layers gives rise to a Moiré superlattice structure with a long spatial period, and it strongly affects the low energy band structure. Here we introduce an effective continuum model based the Dirac equation to describe the electronic structure of TBG [1]. In a magnetic field, the coexistence of the long wavelength superlattice structure and the Landau quantization causes the fractal energy spectrum so-called Hofstadter's butterfly [2]. We describe the spectral evolution of TBG as a function of magnetic field, and demonstrate that the quantized Hall conductivity changes nonmonotonically in changing Fermi energy [3]. We also argue the electronic properties of a similar rotationally stacked system composed of graphene and hexagonal boron-nitride [4], and explain the recent experimental observation.

[1] P. Moon and M. Koshino, Phys. Rev. B 87, 205404 (2013)

[2] D. Hofstadter, Phys. Rev. B 14, 2239 (1976).

[3] P. Moon and M. Koshino, Phys. Rev. B 85, 195458 (2012).

[4] C. R. Dean, L. Wang, P. Maher, et al., Nature 497, 598 (2013).

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