Contents Abbreviations and Symbols iii Fermi velocity W width ξ valley index vi √ 3·a0 = 2.46 Å, and the elementary unit cell (grey area). Red dashed lines indicate nearest and next-nearest neighbor coupling, parametrized by γ0 and γ 0 , respectively. (b) Reciprocal space with the lattice vectors b1 and b2, the 1 st Brillouin zone (BZ, grey area), and the high-symmetry points Γ , M , K, and K . (c) Dispersion of the two π-electronic bands in the 1 st BZ, calculated from Eq. A.2 using γ0 = 3 eV

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... nd γ 0 = 0.1 eV. The inset shows the approximately linear dispersion in the vicinity of the K-point (Dirac cone). (d) Dispersion of electronic states along high-symmetry lines in the 1 st BZ (here, γ 0 is neglected). Arrows indicate the pseudospin orientation for the valence and conduction band in the vicinity of the K ( ) -point. 1.2. BILAYER GRAPHENE * Although higher values of |∆n| have successfully been achieved by this method, dielectric breakdown remains a fundamental limit to eld eect gating, making it dicult to reach values beyond |∆n| = 10 13 cm −2 .