Tuning current-induced electron wind forces for adsorbates on graphene

Abstract

By altering the electronic structure of current-carrying membranes, fine-tuning and optimization of current-induced forces on adsorbates become possible, facilitating the migration of adsorbates on membrane surfaces. This property finds diverse applications in nanoscale systems, including mass transport and ionic current generation. This study explores the adsorption characteristics of NH3 and H2S molecules on graphene surfaces and the accompanying electromigration forces. Using the density functional theory and non-equilibrium Green's function calculations, we demonstrate that under applied gate voltages, a distinct threshold behavior in electromigration forces emerges, dominated by electron wind forces. This effect activates significant electron wind forces only when the orbital energies of the adsorbate align closer to the bias window, in contrast to the inherent alignment seen in resonant adsorbates. The findings elucidate the critical role of orbital energy alignment and electron scattering forces in governing electromigration, offering insights into the adsorbate–electron coupling at interfaces.