Current-induced atomic forces in gated graphene nanoconstrictions

Abstract

Electronic current densities can reach extreme values in highly conducting nanostructures where constrictions limit current. For bias voltages on the 1 volt scale, the highly non-equilibrium situation can influence the electronic density between atoms, leading to significant inter-atomic forces. An easy interpretation of the non-equilibrium forces is currently not available. In this work, we present an ab-initio study based on density functional theory of bias-induced atomic forces in gated graphene nanoconstrictions consisting of junctions between graphene electrodes and graphene nano-ribbons in the presence of current. We find that current-induced bond-forces and bond-charges are correlated, while bond-forces are not simply correlated to bond-currents. We discuss, in particular, how the forces are related to induced charges and the electrostatic potential profile (voltage drop) across the junctions. For long current-carrying junctions we may separate the junction into a part with a voltage drop, and a part without voltage drop. The latter situation can be compared to a nano-ribbon in the presence of current using an ideal ballistic velocity-dependent occupation function. This shows how the combination of voltage drop and current give rise to the strongest current-induced forces in nanostructures.

arXiv comment10 pages, 9 figures

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Cited by in corpus (6)

• Current-induced dissociation in molecular junctions beyond the paradigm of vibrational heating: The role of anti-bonding electronic states
• Unraveling current-induced dissociation mechanisms in single-molecule junctions
• Electric-field control of a single-atom polar bond
• Accessing the spectral function in a current-carrying device
• Removing all periodic boundary conditions: Efficient non-equilibrium Green function calculations
• Simple approach to current-induced effects -- bond weakening in metal chains