Observation of polaron dynamics in magnetic quantum wells

Femtosecond spectroscopic measurements of optically induced magnetization are performed on new type-II ZnTe/${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Se diluted-magnetic-semiconductor heterostructures consisting of magnetic quantum wells confined by nonmagnetic barrier layers. The formation and evolution of electron-based bound magnetic polarons in the wells is observed through static and time-domain experiments. Energy-dependent magnetic spin dynamics on ultrashort time scales are seen to vary dramatically with the degree of electronic confinement.