Study of superfluid 3He films with a micro-electro-mechanical device

Abstract

A micro-electro-mechanical system (MEMS) device with a 1.25 μm gap between a movable plate and the substrate was immersed in superfluid 3He and cooled below 500 μK at 21.2 bar. Mechanical resonances of its shear motion were monitored on warming from the base temperature. Our preliminary results demonstrate increasing damping and decreasing resonance frequencies with temperature, consistent with a thermal damping model caused by thermal quasiparticles. The quality factor (Q) of the oscillator remains surprisingly low (Q 30) down to 0.2 T/Tc, about 4 orders of magnitude smaller than the value in vacuum at 4K. The average superfluid gap was determined to be significantly suppressed from the value in bulk at the corresponding pressure.