# Time-resolved impurity-invisibility in graphene nanoribbons

## TL;DR

This paper explores how impurity atoms affect charge transport in graphene nanoribbons over time, revealing conditions under which impurities become 'invisible' to transport measurements, with implications for ultrafast sensing technologies.

## Contribution

It introduces a time-dependent analysis of impurity effects in graphene nanoribbons, highlighting the role of symmetry and transient behaviors in impurity invisibility.

## Key findings

- Impurity invisibility depends on impurity location and lattice symmetry.
- Transient charge and current profiles reveal impurity effects on transport.
- AC driving can detect lattice-symmetry breaking caused by impurities.

## Abstract

We investigate time-resolved charge transport through graphene nanoribbons supplemented with adsorbed impurity atoms. Depending on the location of the impurities with respect to the hexagonal carbon lattice, the transport properties of the system may become invisible to the impurity due to the symmetry properties of the binding mechanism. This motivates a chemical sensing device since dopants affecting the underlying sublattice symmetry of the pristine graphene nanoribbon introduce scattering. Using the time-dependent Landauer--B{\"u}ttiker formalism, we extend the stationary current-voltage picture to the transient regime, where we observe how the impurity invisibility takes place at sub-picosecond time scales further motivating ultrafast sensor technology. We further characterize time-dependent local charge and current profiles within the nanoribbons, and we identify rearrangements of the current pathways through the nanoribbons due to the impurities. We finally study the behavior of the transients with ac driving which provides another way of identifying the lattice-symmetry breaking caused by the impurities.