Charged excitons in a low magnetic field in $\mathrm{GaAs}/{\mathrm{Ga}}_{1-x}{\mathrm{Al}}_x\mathrm{As}$ and ${\mathrm{C}\mathrm{d}\mathrm{T}\mathrm{e}/\mathrm{C}\mathrm{d}}_{1-x}{\mathrm{Zn}}_x\mathrm{Te}$ semiconductor quantum wells

We study the influence of an external magnetic field on the singlet and triplet ground states of negatively and positively charged excitons in $\mathrm{GaAs}/{\mathrm{Ga}}_{1-x}{\mathrm{Al}}_x\mathrm{As}$ and ${\mathrm{C}\mathrm{d}\mathrm{T}\mathrm{e}/\mathrm{C}\mathrm{d}}_{1-x}{\mathrm{Zn}}_x\mathrm{Te}$ semiconductor quantum wells in the low-field limit. The energies are determined using a variational wave function for finite values of the band offsets. We show that there appear additional Landau levels due to the charge of the center of mass. We discuss the influence of the magnetic field on the exciton and charged excitons transition energies.