4He spectrum shift caused by 3He admixture II
Abstract
The shift Δ E of a maxon-roton 4He excitation spectrum E via the 3He admixture is considered theoretically. The Bogoliubov formula for E( ρ, g) as a function of Bose-condensate density ρ and of 4He/ 4He interaction g is used as an element of partition function formalism of the whole system, presented in the form of a path (functional) integral. The dependence of ρ on g, 4He/ 3He interaction λ as well as on the pressure P, induced by the 3He admixture, is taken into account. The new model of g, suitable for analytical calculations, is used for a description of a change of P within a constant volume. The cases of positive and negative shifts are found as the result of competition between interactions g and λ.
- Publication:
-
Physica A Statistical Mechanics and its Applications
- Pub Date:
- July 2001
- DOI:
- 10.1016/S0378-4371(01)00174-1
- arXiv:
- arXiv:cond-mat/0012403
- Bibcode:
- 2001PhyA..296..337B
- Keywords:
-
- Condensed Matter
- E-Print:
- 10 pages, 1 figure, Submitted to Physica A, gratitude added