We have investigated the influence of an adsorbed helium film on the damping of a torsional oscillator containing exfoliated graphite. The damping depends crucially on the phase of the adsorbed film; in the incommensurate solid a significant dissipation is measured which increases with decreasing temperature. The origin is believed to be internal friction in the two dimensional solid rather than surface friction. The results provide a novel probe of the 2D melting transition. They are being extended to lower temperatures, including an investigation of the domain wall solid phase in order to elucidate the dissipation mechanism.
References (5)
LauterH.J.
Physica B
(1990)
GreywallD.S.
Phys. Rev. B
(1993)
There are more references available in the full text version of this article.
