Dissipation of micro-cantilevers as a function of air pressure and metallic coating

TL;DR

This study investigates how air pressure and metallic coatings affect the internal dissipation of micro-cantilevers by measuring their thermal noise and analyzing their mechanical response.

Contribution

It introduces a method to characterize dissipation in coated micro-cantilevers using thermal noise measurements and response function reconstruction.

Findings

Dissipation varies with air pressure and coating material.

Gold coating thickness influences internal viscoelastic damping.

Mechanical response functions reveal frequency-dependent dissipation.

Abstract

In this letter, we characterize the internal dissipation of coated micro-cantilevers through their mechanical thermal noise. Using a home-made interferometric setup, we achieve a resolution down to 1E-14m/rtHz in the measurement of their deflection. With the use of the fluctuation dissipation theorem and of the Kramers-Kronig relations, we rebuilt the full mechanical response function from the measured noise spectrum, and investigate frequency dependent dissipation as a function of the air pressure and of the nature of the metallic coatings. Using different thicknesses of gold coatings, we discuss the source of the internal viscoelastic damping.