Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 60: Graphene - Theory (jointly with DS, HL, MA, and O)

TT 60.3: Talk

Thursday, March 14, 2013, 15:30–15:45, H17

Subgap conductivity in gated bilayer graphene — •Maxim Trushin — University of Konstanz, 78457 Konstanz

In the present work [1], the subgap electron transport has been investigated in gated bilayer graphene [2] within the two-band effective model using the finite-size Kubo formula. The conductivity does not vanish even though the temperature is set to zero and the chemical potential gets into the middle of the band gap. In contrast to the universal subgap conductivity observed in the 2D topological insulators [3], the subgap conductivity in bilayer graphene turns out to be sensitive to the band gap size and disorder strength.

The effect can be explained in terms of the quantum mechanical interband coherence which turns out to be important for the chiral carriers. At finite temperature, a competition between the temperature-dependent interband decoherence and thermal activation processes results in the non-monotonic conductivity vs. temperature dependence. The non-monotonicity can be seen as a signature of the interband entanglement responsible for the difference between the transport and spectral gaps. The effect can be observed in gapped bilayer graphene sandwiched in boron nitride where the electron-hole puddles and flexural phonons are strongly suppressed.

[1] M. Trushin, Europhys. Lett. 98, 47007 (2012). [2] E. McCann, Phys. Rev. B 74, 161403 (2006). [3] M. Z. Hasan and C. L. Kane, Rev. Mod. Phys. 82, 3045 (2010).