Solid-State Lifshitz-van der Waals Repulsion through Two-Dimensional Materials

TL;DR

This paper demonstrates that two-dimensional materials can induce Lifshitz-van der Waals repulsion in a vacuum, enabling new ways to control nanoscale interactions and influence epitaxial growth.

Contribution

The study provides the first direct force measurement of vdW repulsion with 2D materials in vacuum, revealing their potential to tailor quantum fluctuation-induced forces.

Findings

Direct measurement of vdW repulsion on 2D surfaces

Ultrafast diffusion of gold clusters on graphene due to repulsion

Influence of vdW repulsion on heteroepitaxial growth

Abstract

In the 1960s, Lifshitz et al. predicted that quantum fluctuations can change the van der Waals (vdW) interactions from attraction to repulsion. However, the vdW repulsion, or its long-range counterpart - the Casimir repulsion, has only been demonstrated in liquid. Here we show that the atomic thickness and birefringent nature of two-dimensional materials make them a versatile medium to tailor the Lifshitz-vdW interactions. Based on our theoretical prediction, we present direct force measurement of vdW repulsion on 2D material surfaces without liquid immersion and demonstrate their substantial influence on epitaxial properties. For example, heteroepitaxy of gold on a sheet of freestanding graphene leads to the growth of ultrathin platelets, owing to the vdW repulsion-induced ultrafast diffusion of gold clusters. The creation of repulsive force in nanoscale proximity offers technological opportunities such as single-molecule actuation and atomic assembly.