Non-contact dissipation on the surface of charge density wave materials

TL;DR

This paper introduces a nanoscale mechanism for mechanical dissipation peaks caused by charge-density-wave phase slips, explaining recent AFM experiments on CDW materials like NbSe2.

Contribution

It proposes a novel local surface mechanism involving 2π phase slips that cause dissipation peaks, advancing understanding of CDW surface dynamics.

Findings

Mechanical dissipation peaks linked to 2π phase slips in CDWs

Numerical simulations match experimental observations on NbSe2

Predicts similar effects in other CDW systems

Abstract

Bulk electrical dissipation caused by charge-density-wave (CDW) depinning and sliding is a classic subject. We present a novel local, nanoscale mechanism describing the occurrence of mechanical dissipation peaks in the dynamics of an atomic force microscope tip oscillating above the surface of a CDW material. Local surface 2$\pi$ slips of the CDW phase are predicted to take place giving rise to mechanical hysteresis and large dissipation at discrete tip surface distances. The results of our static and dynamic numerical simulations are believed to be relevant to recent experiments on NbSe$_2$; other candidate systems in which similar effects should be observable are also discussed.