Collective excitations in a stratified helium film

Collective excitations of a stratified film of a He3–He4 solution on a solid substrate are studied. It is shown that the excitation spectrum contains two branches whose structure is determined by the interaction of the liquid phases caused by the van der Waals’ forces, with both the substrate and with each other. The dispersion law of the collective excitations is investigated for different relationships between the thicknesses of the phases (d1 and d2) It is shown that taking account of the interaction between the stratified liquid phases of the solution results in the two speeds of sound in the solution becoming closer in the region d1 ∼ d2.

Ҳали таржима қилинмаган