Effective tunnel conductance and effective ac conductivity of randomly strained graphene

摘要

We consider a single-layer graphene with high ripples, so that the pseudomagnetic fields due to these ripples are strong. If the magnetic length corresponding to a typical pseudomagnetic field is smaller than the ripple size, the resulting Landau levels are local. Then the effective properties of the macroscopic sample can be calculated by averaging the local properties over the distribution of ripples. We find that this averaging does not wash out the Landau quantization completely. Average density of states (DOS) contains a feature (inflection point) at energy corresponding to the first Landau level in a typical field. Moreover, the frequency dependence of the ac conductivity contains a maximum at a frequency corresponding to the first Landau level in a typical field. This nontrivial behavior of the effective characteristics of randomly strained graphene is a consequence of nonequidistance of the Landau levels in the Dirac spectrum.