Ultrafast exciton spin dynamics in Cd _{1− x} Mn _x Te quantum wells studied by transient pump‐probe spectroscopy

Abstract

. Pump-probe transient spectroscopy is one of the most powerful methods to discriminate the ultrafast dynamics of the optically prepared e-h plasma, excitons and the subsequent spin dynamics of local magnetic moments [2][3][4]. In this work, we studied the formation and relaxation dynamics of the exciton interacting with the local spin system of magnetic ions in DMS quantum wells (QWs) by using transient pump-probe spectroscopy in magnetic fields. The study reveals the dynamical band-gap renormalization (BGR) due to the exchange-correlation of the dense carriers, the formation of excitonic magnetic polaron (EMP) and the long-lived feature of the spin alignment for the magnetic ions within EMPs.

Ultrafast spin injection from Cd1−Mn Te magnetic barriers into a CdTe quantum well studied by pump–probe spectroscopy

“…The period of the QW structure was 30. Pump-probe absorption spectroscopy was performed in magnetic fields [4,5]. The experimental set-up for the pump-probe measurement is described in detail elsewhere [6].…”

Transient photoluminescence spectroscopy of spin injection dynamics in double quantum wells of diluted magnetic semiconductors

“…However the time resolution of the streak camera system is not sufficient to clarify faster spin processes. For the purpose to resolve the faster spin dynamics, we employed the pump-and-probe transient absorption spectroscopy with the circular polarization analysis [7][8][9]. The sample used is a Cd 0.95 Mn 0.05 Te/Cd 0.75 Mg 0.25 Te quantum well (QW).…”

Trend reversal in the magnetic-field dependence of exciton spin-transfer rates in diluted magnetic semiconductors due to non-Markovian dynamics

“…However, fundamental observations in the ultrafast spin dynamics in these systems remain not understood, as evident by the persistent underestimation of measured spin-transfer rates by calculations using Fermi's golden rule for quasi-free electrons as well as an observed nonmonotonic dependence of the transverse spin relaxation on magnetic field 13,14 . It has been argued that some of the discrepancies between theory and experiment are the result of probing excitons rather than quasi-free carriers since typical experiments are performed at the exciton resonance 10,12,14,15,[18][19][20][21] . However, a simple replacement of the electron mass by the exciton mass in Fermi's golden rule strongly overestimates the spin decay.…”