Physics – Condensed Matter – Statistical Mechanics
Scientific paper
2002-03-04
Physics
Condensed Matter
Statistical Mechanics
28 pages, 4 figures
Scientific paper
10.1103/PhysRevA.65.063602
The ground states of Bose-Einstein condensates of spin-2 bosons are classified into three distinct (ferromagnetic, ^^ ^^ antiferromagnetic", and cyclic) phases depending on the s-wave scattering lengths of binary collisions for total-spin 0, 2, and 4 channels. Many-body spin correlations and magnetic response of the condensate in each of these phases are studied in a mesoscopic regime, while low-lying excitation spectra are investigated in the hermodynamic regime. In the mesoscopic regime, where the system is so tightly confined that the spatial degrees of freedom are frozen, the exact, many-body ground state for each phase is found to be expressed in terms of the creation operators of pair or trio bosons having spin correlations. These pairwise and trio-wise units are shown to bring about some unique features of spin-2 BECs such as a huge jump in magnetization from minimum to maximum possible values and the robustness of the minimum-magnetization state against an applied agnetic field. In the thermodynamic regime, where the system is spatially uniform, low-lying excitation spectra in the presence of magnetic field are obtained analytically using the Bogoliubov approximation. In the ferromagnetic phase, the excitation spectrum consists of one Goldstone mode and four single-particle modes. In the antiferromagnetic phase, where spin-singlet ^^ ^^ pairs" undergo Bose-Einstein condensation, the spectrum consists of two Goldstone modes and three massive ones, all of which become massless when magnetic field vanishes. In the cyclic phase, where boson ^^ ^^ trios" condense into a spin-singlet state, the spectrum is characterized by two Goldstone modes, one single-particle mode having a magnetic-field-independent energy gap, and a gapless single-particle mode that becomes massless in the absence of magnetic field.
Koashi Masato
Ueda Masahito
No associations
LandOfFree
Theory of spin-2 Bose-Einstein condensates: spin-correlations, magnetic response, and excitation spectra does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Theory of spin-2 Bose-Einstein condensates: spin-correlations, magnetic response, and excitation spectra, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Theory of spin-2 Bose-Einstein condensates: spin-correlations, magnetic response, and excitation spectra will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-335251