BINDING-ENERGY OF EXCITONS IN MAGNETICALLY MIXED SEMICONDUCTORS SUBJECTED TO A MAGNETIC-FIELD

A hexagonal mapetically mixed semiconductor with its energy bands spin-split by an effective exchange field G is investigated. The binding energy R(ex) of excitons formed by carriers from specific spin subbands is determined. It is shown that in the specific case when H parallel-to c6 (H is the external magnetic field and c6 is the sixfold axis of the semiconductor), the field G(parallel-to H) may have a significant influence on the effective masses in the B and C hole subbands and the influence may be different for different spin states. The result is the appearance of a dependence of R(ex) on G for excitons representing these hole subbands. Numerical estimates obtained for Cd1-xMnxS show that the exciton binding energy depends on the magnetic field which changes significantly the splitting of the pi-components of the exciton transitions.