Magnetic properties of charged spin-1 Bose gases with ferromagnetic coupling

Abstract

The magnetic properties of a charged spin-1 Bose gas with ferromagnetic interactions are investigated within mean-field theory. It is shown that a competition between paramagnetism, diamagnetism and ferromagnetism exists in this system. It is shown that diamagnetism, being concerned with spontaneous magnetization, cannot exceed ferromagnetism in a very weak magnetic field. The critical value of reduced ferromagnetic coupling of the paramagnetic phase to ferromagnetic phase transition I[combining overline](c) increases with increasing temperature. The Landé-factor g is introduced to describe the strength of the paramagnetic effect which comes from the spin degree of freedom. The magnetization density M[combining overline] increases monotonically with g for fixed reduced ferromagnetic coupling I[combining overline] as I[combining overline] > I[combining overline](c). In a weak magnetic field, ferromagnetism makes an immense contribution to the magnetization density. On the other hand, at a high magnetic field, the diamagnetism tends to saturate. Evidence for condensation can be seen in the magnetization density at a weak magnetic field.

Magnetic properties of spin-1/2 Fermi gases with ferromagnetic interaction

“…We can find that the value ofĪ c increases linearly with the increase of temperature. The results is similar to the Bose gas with FM coupling [14], although they submit to different statistical rules, respectively. It indicates that the crossover from paramagnetic phase to FM phase is more difficult with increasing the temperature.…”

“…Our results uncover a competition among paramagnetism, diamagnetism and ferromagnetism. We also present a comparison with the results of charged spin-1 Bose gas with FM interactions which have been obtained previously [14]. As the increase of temperature, there is not a pseudo-critical temperature for the charged spin-1/2 Fermi gases with FM interaction, which is different from the case of Bose gas.…”

“…That is ferromagnetism cooperates with paramagnetism to confront diamagnetism in a finite magnetic field. This is different from the result of the Bose gas with FM coupling [14]. Where it is faintly affected by the FM coupling in the evolvement of magnetization density with g. Figure 4 is plotted to get more insight of the dependence of the magnetization density on magnetic field.…”

“…which can be evaluated from figure 1. The internal field comes from the spontaneous magnetization results in the diamagnetism [14]. Figure 1 shows that ferromagnetism exceeds the diamagnetism with increasing Ī.…”

“…We have extended it to further study the competition between diamagnetism and paramagnetism of charged spin quantum gases [19,20]. As far as FM interaction is concerned, it is shown that the meanfield theory is still effective in understanding the main physics of magnetism [12,14,15]. Some compact notations for the class of sums are introduced for simplicity,…”