Transport properties of graphene in proximity with alkali metals

Abstract

Abstract In this work, we propose the analysis of the electronic and transport properties of graphene decorated with Lithium and Potassium adatoms. We will study two inequivalent metal adsorption sites: the Top site, on top of a carbon atom of one sub-lattice of graphene; and the Hollow site, in the middle of a C6-unit. With this end, we will use an analytical Tight Binding Model, for graphene with adsorbate atoms of lithium and potassium, for the two different adsorption positions. Then, we use the Green’s function equation of motion method to calculate the corresponding band structures and density of states, and numerical calculations for the conductance are performed with the quantum transport simulation package of python (Kwant). We find that the bands are down shifted with respect to pristine graphene, indicating a doping with electrons. For the Top case, the AB symmetry breaking produced in this configuration, generates small bandgaps of approximately 170 meV for potassium and 220 meV for lithium. Finally, the conductance is shifted in energy in the same way as the bands, preserving its growing rate with the absolute value of the energy as for pristine graphene.