  The expected features of diluted magnetic semiconductors still remain in
controversial issue, concerning whether or not s, p-d (f) exchange interactions
indeed modify the host semiconductor band structure. To solve this doubt, a new
scheme for measuring magneto-optical (MO) effect is developed, called magnetic
photoresistance circular dichroism (PR-MCD), which detects the differential
photoresistance of materials between two circularly polarized excitations. That
allows us to detect the MO effect induced only by interband transitions, and
provide unambiguous evidence that the host semiconductor band structure is
indeed modified by the strong exchange interactions. Our PR-MCD spectra also
disclose intrigue features which may come from strong coupling correlation
effect at very high manganese concentration limit.
