Selected Publications

Observation of Zero-Sound at Atomic Wave-Vectors in a Monolayer of Liquid 3He

H. Godfrin, M. Meschke, H.-J. Lauter, H.M. Böhm, E. Krotscheck, M. Panholzer

The elementary excitations of a strongly interacting two-dimensional Fermi liquid have been investigated by inelastic neutron scattering in an experimental model system: a monolayer of liquid 3He adsorbed on graphite preplated by a monolayer of solid 4He. We observed for the first time the particle-hole excitations characterizing the Fermi liquid state of two-dimensional liquid 3He, and we were also able to identify the highly interesting zero-sound collective mode above a particle-hole band. Contrarily to bulk 3He, at low wave-vectors this mode lies very close to the particle-hole band. At intermediate wave-vectors, the collective mode enters the particle-hole band, where it is strongly broadened by Landau damping. At high wave-vectors, where the Landau theory is not applicable, the zero-sound collective mode reappears beyond the particle-hole band as a well defined excitation, with a dispersion relation quite similar to that of superfluid 4He. This spectacular effect is observed for the first time in a Fermi liquid (including plasmon excitations in electronic systems).

J. Low Temp. Phys. 158, 147 (2010)

doi: 10.1007/s10909-009-9952-5