EXCHANGE ENERGIES, BOUND MAGNETIC POLARONS, AND MAGNETIZATION IN CDSE-CO AND CDS-CO

The sp-d exchange energies, bound magnetic polarons, and magnetization have been studied in Cd1-xCoxSe and Cd1-xCoxS. For x=0.02-0.05, magnetization measurements of the Co2+ ions at liquid-helium temperatures are adequately described by a modified Brillouin function for pure spin S=3/2 ions. In spin-flip Raman-scattering (SFRS) measurements from donor-bound electrons we observe a large Zeeman splitting of ∼4-10 meV at high magnetic fields, and bound magnetic polaron energies of 0.2-0.4 meV at B=0. The s-d exchange energy between conduction electrons and Co2+ ions, obtained by combining the SFRS and magnetization results, is found to be αN0=274±6 meV for CdSe, and αN0=179±4 meV for CdS. For Cd1-xCoxSe, from reflectivity measurements and the αN0 value we obtain βN0=-2120±50 meV. © 1995 The American Physical Society.