Strong energetic anomaly of charged excitons in atwo-dimensional electron system at low temperatures andhigh magnetic fields

摘要

In photoluminescence and absorption experiments we have observed a stronganomaly in the magnetic-field dispersion of negatively charged excitons in dilute twodimensionalelectron systems. The anomaly exists in an intermediate density range around1 × 1011 cm-2, and at temperatures T < 1 K, only. The strength of the anomaly at T = 0.1K is about 2.5 meV, and the most intriguing feature is that it can be completely destroyedby a small thermal energy of about 0.2 meV (2 K). The anomaly can be observed both inphotoluminescence and direct absorption measurements.