Competition between paramagnetism and diamagnetism in charged Fermi gases

The charged Fermi gas with a small Lande-factor g is expected to be diamagnetic, while that with a larger g could be paramagnetic. We calculate the critical value of the g  -factor which separates the dia- and paramagnetic regions. In the weak-field limit, gcgc has the same value both at high and low temperatures, gc=1/12. Nevertheless, gcgc increases with the temperature reducing in finite magnetic fields. We also compare the gcgc value of Fermi gases with those of Boltzmann and Bose gases, supposing the particle has three Zeeman levels σ=±1,0σ=±1,0, and find that gcgc of Bose and Fermi gases is larger and smaller than that of Boltzmann gases, respectively.