MAGNETOOPTICAL INVESTIGATIONS OF DILUTED CD1-XMNXS MAGNETIC SEMICONDUCTORS IN THE B-EXCITON REGION

The measurements of magnetoreflection spectra in the B-exciton region of diluted magnetic semiconductors (DMS's) Cd1-xMnxS are carried out f or the magnetic-field directions both along and across the crystal c a xis. It is pointed out that giant spin splitting (GSS) of the B excito n does not demonstrate a nonlinear dependence on the magnetic-componen t fractional content x, contrary to the A-exciton GSS situation. It is supposed that the effects of multiple scattering of valence electron on the magnetic ions, which lead to a sublinearity of the A-exciton GS S x dependence in Cd1-xMnxS, are different for the A and B valence-ele ctron subbands. In particular, due to a smaller effective mass of vale nce electrons in the B subband, the multiple scattering of this electr on on Mn2+ ions may be not important and the GSS of B excitons can be described by the mean-field approximation (MFA) with the ''bare'' exch ange constant J(h) for B-hole interactions with magnetic ions. The app roach to the determination of band parameters Delta(1), Delta(2), Delt a(3) and the hole-ion exchange constant J(h) in hexagonal DMS's is sug gested. This approach is based only on the B-exciton GSS MFA descripti on and data of energy distances between A, B, and C excitons. The meth od is applied far the treatment of exciton magnetoreflection spectra o f Cd1-xMnxS crystals with different x. It is established that J(h) = - 1.7 eV and is independent of x. This value J(h) turns out to be severa l times smaller than that obtained from MFA for A-exciton GSS. However , this value is in good agreement with J(h) = -1.4 eV, the value obtai ned earlier from the A-exciton GSS treatment beyond the MFA. In the li miting case of small x, we obtained the band parameter values Delta(1) = 17.2 +/- 2 meV, Delta(2) = 25.6 +/- 0.7 meV, and Delta(3) = 21.7 +/ - 0.3 meV. They differ from those known in the literature for purr CdS .