Nano-corrugation induced forces between electrically neutral plasmonic objects

TL;DR

This paper reveals a new curvature-induced force between neutral plasmonic surfaces caused by nano-scale corrugation, which is not explained by classical electromagnetism and is comparable to light-induced forces.

Contribution

It introduces a novel curvature-induced force in nano-plasmonic systems, derived from a hydrodynamics model and density functional calculations, highlighting geometric effects on nano-scale forces.

Findings

Force can be attractive or repulsive depending on nano-corrugation details.

Magnitude of the force is comparable to light-induced forces on plasmonic nano-objects.

Standard classical electromagnetic approaches cannot capture this force.

Abstract

Recent advances in nanotechnology have created tremendous excitement across different disciplines but in order to fully control and manipulate nano-scale objects, we must understand the forces at work at the nano-scale, which can be very different from those that dominate the macro-scale. We show that there is a new kind of curvature-induced force that acts between nano-corrugated electrically neutral plasmonic surfaces. Absent in flat surfaces, such a force owes its existence entirely to geometric curvature, and originates from the kinetic energy associated with the electron density which tends to make the profile of the electron density smoother than that of the ionic background and hence induces curvature-induced local charges. Such a force cannot be found using standard classical electromagnetic approaches, and we use a self-consistent hydrodynamics model as well as first principles density functional calculations to explore the character of such forces. These two methods give qualitative similar results. We found that the force can be attractive or repulsive, depending on the details of the nano-corrugation, and its magnitude is comparable to light induced forces acting on plasmonic nano-objects.