Low-temperature magneto-photoluminescence studies of negatively charged excitons (X- trions) are reported for n-type modulation-doped ZnSe/Zn(Cd,Mn)Se quantum wells over a wide range of Fermi energy and spin-splitting. The magnetic composition is chosen such that these magnetic two-dimensional electron gases (2DEGs) are highly spin-polarized even at low magnetic fields, throughout the entire range of electron densities studied (5e10 to 6.5e11 cm^-2). This spin polarization has a pronounced effect on the formation and energy of X-, with the striking result that the trion ionization energy (the energy separating X- from the neutral exciton) follows the temperature- and magnetic field-tunable Fermi energy. The large Zeeman energy destabilizes X- at the nu=1 quantum limit, beyond which a new PL peak appears and persists to 60 Tesla, suggesting the formation of spin-triplet charged excitons.
@article{arxiv.cond-mat/0001396,
title = {Stability of trions in strongly spin-polarized two-dimensional electron gases},
author = {S. A. Crooker and E. Johnston-Halperin and D. D. Awschalom and R. Knobel and N. Samarth},
journal= {arXiv preprint arXiv:cond-mat/0001396},
year = {2009}
}
Comments
5 pages (RevTex), 4 embedded EPS figs. Submitted to PRB-RC