We observed a giant splitting of exciton spin sublevels in CdS nanocrystals
, each doped on the average by one Mn ion. The splitting, which exists in z
ero external magnetic field, is caused by the gigantic internal magnetic fi
eld of the Mn ion and results from the enhancement of the short range spin-
spin interactions in nanocrystal quantum dots. The splitting is seen in the
strong magnetic circular dichroism of the CdS band edge transitions. The m
agnitude of the observed band edge splitting is in good agreement with a th
eoretical calculation of the effective magnetic field. (C) 2000 Published b
y Elsevier Science Ltd. All rights reserved.