Anomalous g-factors and diamagnetic shifts of biexcitons in ZnS quantum wells

We present a magneto-optical study of biexcitons confined within ZnS quantum wells at fields up to View the MathML source. We have measured the luminescence energy splitting of these excitonic systems and find that the results contrast with the conventional picture of biexcitons in a magnetic field in which the luminescence splitting is entirely determined by the splitting (g-factor) of the exciton. Our results suggest that biexcitons are much more complex than previously thought and that the additional confinement and Coulomb interaction within the quantum wells must be taken into account.