A. Lemaitre et al., Magneto-optical evidence of many-body effects in a spin-polarized two-dimensional electron gas, PHYS REV B, 62(8), 2000, pp. 5059-5065
Modulation-doped CdxMn1-xTe/CdyMg1-yTe quantum wells are studied at 1.7 K b
y magnetoabsorption experiments performed near the fundamental heavy-hole-e
lectron (HH1-E-1) transition. In the investigated range of Mn content (x ap
proximate to 0.02) and electron concentration [n(e)approximate to(2-3)X10(1
1)cm-(2]), the two-dimensional electron gas is fully spin-polarized at magn
etic fields as low as H=1.5 T. The interband optical spectra exhibit unusua
l magnetic field dependence resulting from electron-hole interactions and p
hase-space-filling effects. An additional enhancement of the spin splitting
of Landau levels found in this study is attributed to the electron-exchang
e interaction. A simplified theoretical model including the exchange energy
and the electron-hole interaction provides a coherent quantitative descrip
tion of the overall experimental features.