Measurement of exciton lifetime in double semimagnetic quantum well by means of magneto-optical Kerr effect

Magneto-optical Kerr effect caused by weak oscillating magnetic field in Faraday geometry was used for measuring of the exciton radiative $\Gamma_0$ and nonradiative $\Gamma$ damping rates in semimagnetic quantum well $\mathrm{Cd}_{0.984}\mathrm{Mn}_{0.016}\mathrm{Te}$, separated from more wide nonmagnetic quantum well $\mathrm{CdTe}$ by tunnel-transparent barrier. Measured values in energetic units were found to be $\hbar\Gamma_0\approx114$ $\mu$eV and $\hbar\Gamma\approx 4.6$ meV. Large value of $\Gamma$ means that the time of carriers tunneling from narrow well to wide one is shorter than $0.1$ ps.