TY  - JOUR
AU  - Mateo, D.
AU  - Barranco, M.
AU  - Navarro, J.
PY  - 2010
DA  - 2010//
TI  - Elementary excitations in superfluid He-3-He-4 mixtures
T2  - Phys. Rev. B
JO  - Physical Review B
SP  - 134529
EP  - 13pp
VL  - 82
IS  - 13
PB  - Amer Physical Soc
AB  - We have studied the dynamic structure function of superfluid He-3-He-4 mixtures at zero temperature as a function of pressure and He-3 concentration. Results obtained in the full random-phase approximation (RPA) plus density-functional theory and in a generalized Landau-Pomeranchuk approach are presented and compared with experiment. Analytic expressions for several sum rules of the dynamic structure functions have been determined, and have been used to obtain average energies of the collective excitations. In the RPA approach, the dispersion relation of the collective modes shows typical features of level repulsion between zero-soundlike and phonon-rotonlike excitations. The structure of the coupled RPA equations for the mixture leads in a natural way to the hybridization of the collective modes. The mixed He-3-He-4 dynamic structure function quenches the zero-soundlike mode before it crosses the phonon-roton branch, causing that the former mode only appears with enough strength after the crossing.
SN  - 1098-0121
UR  - https://doi.org/10.1103/PhysRevB.82.134529
DO  - 10.1103/PhysRevB.82.134529
LA  - English
N1  - ISI:000283291200005
ID  - Mateo_etal2010
ER  -