Spin relaxation in CdTe quantum dots

We have measured photoluminescence (PL) spectra and time-resolved PL in CdTe quantum dots under the longitudinal magnetic field up to 10 T. Circular polarization of PL increases with increasing magnetic field, while its linear polarization remains zero under linearly polarized excitation. This behavior cannot be explained by the anisotropic exchange interaction of excitons. Time-resolved PL measurements clarified that this behavior is caused by the suppression of spin relaxation induced by the longitudinal magnetic field. We believe that this behavior is related to the hyperfine interaction of electron spin with magnetic momenta of lattice nuclei.