Diamagnetism versus paramagnetism of charged ideal spin-1/2 fermions in a harmonic trap under a uniform magnetic field

摘要

Magnetic properties of harmonically trapped charged ideal spin-1/2 fermions in a uniform magnetic field are studied. It is shown that the magnetism of charged spin-1/2 fermions can be explained by a competition between the diamagnetic and paramagnetic effects, where a variable spin factor is introduced to describe the strength of paramagnetic effect. As the spin factor increases, a crossover from diamagnetic region to paramagnetic region appears. Moreover, the critical values of spin factor are obtained at low-temperature and under weak magnetic field, respectively. Spin-1/2 fermions display distinct magnetic behaviors from spinless case.