On-Device Control of Electronic Friction

TL;DR

This study demonstrates that electronic friction can dominate energy dissipation in ultra-smooth 2D interfaces, providing new insights into friction mechanisms and enabling on-device control of electronic and phononic contributions.

Contribution

We developed an on-device experimental platform to disentangle electronic and phononic friction contributions, revealing electronic friction's dominance at superlubricity contacts.

Findings

Electronic friction can surpass phononic friction in energy dissipation.

Electrical and mechanical controls can tune interfacial electronic coupling.

Experimental and theoretical results support the dominance of electronic friction.

Abstract

Friction causes mechanical energy dissipation and material degradation in machinery and devices. While phononic friction is well understood via anharmonic lattice dynamics, the physics of electronic friction remains unclear due to challenges in separating electronic degrees of freedom from phononic ones in experiments and analyzing the non-equilibrium interactions between ionic movement and electronic dynamics in theory. To tackle this problem, we construct a sliding device featuring 2D crystalline interfaces that possess ultra-smooth and minimally interacting surfaces, achieving the state of structural superlubricity with no wear and minimal friction. Using electrical and mechanical controls, we tuned the nature of interfacial electronic coupling and charge densities in materials in an on-device setting, which allows us to disentangle the electron and phonon contributions to friction. Our experimental data and theoretical analysis supported by first-principles calculations demonstrate that electronic friction can well surpass phononic contributions and dominate energy dissipation at structural superlubricity contacts. These findings offer fresh insights into the mechanism of electronic friction and promising opportunities for friction control in device applications.