Trion motion in modulation-doped magnetic semiconductor quantum well: Control and observation

We studied the time and spatial-resolved circular-polarized photoluminescence (PL) on n-type modulation-doped (Cd,Mn)Te quantum well, i.e., diluted magnetic semiconductor based two-dimensional electron system (DMS-based 2DES). The studied sample has a 5% Mn composition and electron density of 2×1011 cm−2. The measurements were performed at 4 K using a fluorescence-microscope-based system. Magnetic fields up to 0.5 T were applied in the Faraday geometry. The PL spatial extent in the right circular polarization (RCP) increased with an increase in the magnetic fields, although the PL extent in the left one (LCP) showed a tendency to contract with the magnetic fields. We tried to control the in-plane motion of a trion (X−) using electric fields. The time-development of an electric-field-induced drift of X− was successfully observed through the position shift in the spatial profile of the luminescence. Moreover, the drift was found to be promoted by the magnetic fields. These peculiar phenomena originate in the mutual coupling between the excitonic properties of 2DES and the DMSʹs distinctive properties.