Probing semiconductor carrier kinetics with ultrafast nonlinear Faraday rotation

We demonstrate that in semiconductors with strong Coulomb exchange correlat ions, transient nonlinear Faraday rotation spectroscopy (FRS) more accurate ly probes the ultrafast carrier relaxation than the widely used differentia l transmission spectroscopy (DTS). We calculate nonlinear FRS and DTS by so lving the six-band semiconductor Bloch equations for magnetic Cd1-xMnxTe an d CdTe quantum wells. We show that for highly excited carriers, nonlinear F RS rotation spectra closely monitor the ultrafast thermalization of the car rier distribution, unlike DTS signals. We further show that the magnetic ba nd tuning capabilities (giant Zeeman splitting) of dilute magnetic semicond uctors allows one to investigate the electron kinetics in selective bands. [S0163-1829(98)50844-2].