Static properties and spin dynamics of the ferromagnetic spin-1 Bose gas   in magnetic field
  Properties of spin-1 Bose gases with ferromagnetic interaction in the presence of a nonzero magnetic field are studied. The equation of state and thermodynamic quantities are worked out with the help of a mean-field approximation. The phase diagram besides Bose-Einstein condensation contains a first order transition where two values of the magnetization coexist. The dynamics is investigated with the help of the Random Phase Approximation. The soft mode corresponding to the critical point of the magnetic phase transition is found to behave like in conventional theory. 
Krisztian Kis-Szabo, Peter Szepfalusy, Gergely Szirmai