Anisotropic minimal conductivity of graphene bilayers

作者：Moghaddam Ali G^*; Zareyan Malek

来源：Physical Review B, 2009, 79(7): 073401.

DOI：10.1103/PhysRevB.79.073401

• ballistic transport
• conduction bands
• electrical conductivity
• graphene

The Fermi line of bilayer graphene at zero energy is transformed into four separated points positioned trigonally at the corner of the hexagonal first Brillouin zone. We show that as a result of this trigonal splitting the minimal conductivity of an undoped bilayer graphene strip becomes anisotropic with respect to the orientation theta of the connected electrodes and finds a dependence on its length L on the characteristic scale center dot=pi/Delta k similar or equal to 50 nm determined by the inverse of k-space distance of two Dirac points. The minimum conductivity increases from a universal isotropic value sigma(min)(perpendicular to)=(8/pi)e(2)/h for a short strip L center dot varies from (7/3)sigma(min)(perpendicular to) at theta=0 to 3 sigma(min)(perpendicular to) over an angle range Delta theta similar to center dot/L.

• 出版日期2009-2