1202.3398 (P. A. Andreev)

Self-consistent spin waves in magnetized BEC    [PDF]

P. A. Andreev

We obtain equations of quantum hydrodynamic (QHD) for magnetized spin-1
neutral Bose-Einstein condensate (BEC). System of QHD equations contains the
equation of magnetic moment evolution (an analog of the Bloch equation). We
account spin-spin interaction along with the short range interaction. We
consider self-consistent field approximation of QHD equations. Starting from
QHD equation we derive the Gross-Pitaevskii equation for magnetized BEC. We
show that Gross-Pitaevskii equation exists under condition that the magnetic
moment direction is not change. Using obtained QHD equations we study the
dispersion of collective excitation. As in electrically polarized BEC [P. A.
Andreev, L. S. Kuz'menkov, arXiv: 1201.2440], in the magnetically polarized BEC
there is second wave mode (polarization mode or spin wave), in addition to the
Bogoliubov's mode. Second wave solution appears due to the magnetic moment
evolution. The influence of magnetization on dispersion of Bogoliubov's mode is
found. We found strong difference of dispersion properties of waves in
magnetized BEC from electrically polarized BEC.

View original: http://arxiv.org/abs/1202.3398