Susanne Leitherer: Current-induced atomic forces in gated graphene nanoconstrictions

Susanne Leitherer, Nick R. Papior, and Mads Brandbyge Department of Physics, Technical University of Denmark The interplay between the applied field, current and the atomic structure in ballistic nanoscale conductors carrying a substantial current, as seen in experiments [1], is still not well understood. In this work, we present an ab-initio study based on density functional theory combined with non-equilibrium Greens functions [2] of bias-induced atomic forces in graphene nanoconstrictions in the presence of current [3]. The junctions, consisting of graphene nanoribbons connected to pristine graphene electrodes, are gated to increase their conductance and to allow switching between electron and hole-dominated transport. We show how the forces can be rationalized in terms of bond currents and charge redistribution, in particular induced bond charges, and discuss the role of the electrostatic potential profile (voltage drop) across the junctions. Our results reveal how the combination of voltage drop and current give rise to the strongest current-induced forces in nanostructures. [1] C. Schirm, M. Mat, F. Pauly J.C. Cuevas, P. Nielaba and E. Scheer, Nat.Nanotechnol. 8, 645-648 (2013) [2] N. Papior, N. Lorente, T. Frederiksen, A. Garcia and M. Brandbyge, Comput. Phys. Commun 212, 8 (2017) [3] S. Leitherer, N. Papior and M.Brandbyge, Phys. Rev. B 100, 035415 (2019) Susanne Leitherer is currently a postdoc at DTU Physics in Denmark. Her main research interests are oriented towards the description of electron transport and current-induced dynamics in atomistic/molecular systems at nonequilibrium, including nanoscale devices based on graphene. She completed her PhD in Physics in 2016 at the University of Erlangen-Nuermberg in Germany working on the theory and simulation of charge transport in Carbon-based nanostructures.