The bound magnetic polaron (BMP) in the Van Vleck semimagnetic semiconductor ${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Fe}}_{\mathit{x}}$Se has been investigated. Anticrossing of Raman lines (that of a donor-electron-spin flip and that of an intra-${\mathrm{Fe}}^{2+}$-ion excitation) have been observed in the presence of a magnetic field in the directions parallel and perpendicular to the hexagonal c axis. Selection rules for these Raman transitions at resonance with the exciton bound to a neutral donor are reported and discussed. An overall quantitative agreement between theory and experiment is achieved in a model that takes into account the exchange coupling of the donor electron with the one- and two-ion excitation states of the BMP. For x=1.8 at. %, the BMP is characterized by an exchange shift of its ground state Δ${\mathit{E}}_{\mathit{p}}$=-0.17 ${\mathrm{cm}}^{\mathrm{-}1}$ and a local spin polarization at its center equal to 0.06 (H⊥c) or 0.10 (H?c). To a first approximation, we argue that the Van Vleck BMP behaves like a localized quantum spin 1/2 with a large effective g factor, anisotropic in our material (13.5 for H⊥c and 22 for H?c).

• Received 29 August 1990

DOI:https://doi.org/10.1103/PhysRevB.43.7109