Mechanical response of 4He films adsorbed on single-crystalline graphite

Abstract

We carried out quartz crystal microbalance (QCM) experiments of a 32 kHz quartz tuning fork for 4He films adsorbed on exfoliated single-crystalline graphite and measured the temperature dependence of the resonance frequency and Q value for various areal densities. To study the sliding direction dependence, two quartz tuning forks oscillating in the different crystal directions were prepared. It was found that the resonance frequency does not decrease greatly in the monolayer region and the decoupling from the oscillating substrate is enhanced compared with Grafoil. We observed, however, a weak decrease in frequency around the commensurate phase of monolayer and this decrease shows the sliding direction dependence. © Published under licence by IOP Publishing Ltd.