J. Phys. IV France 10 (2000) Pr7-181-Pr7-184
The peaked structure of phonon density of states of a confined superfluid - a theoretical prediction, and discussions regarding its experimental probeJ.X. Zheng-Johansson1, 2 and B. Johansson3
1 Theoretical Physics Group, Department of Physics, Linköping University, 58183 Linköping, Sweden
2 The Zheng-Johansson Publishing, Stockholmsvägen 14,61137 Nyköping, Sweden.
3 Condensed Matter Theory Group, Department of Physics, Uppsala University, Box 530, 75121 Uppsala, Sweden
We report on an exact, first principles result which shows that when the superfluid of 4He is spatially confined, gaps are created in the phonon excitation energy and that the phonon density of states (PDOS) presents sharp peaks positioned at the gap edges. This finding complements our knowledge of the physics occurring in a spatially confined quantum system, for the superfluid of 4He in particular, this has been shown to result in the critical velocity of a flow motion. Here, we first derive an exact expression of the PDOS of a confined superfluid, and then discuss related aspects regarding the probing of the detailed structure of the peaked PDOS using inelastic neutron scattering.
© EDP Sciences 2000