Effect of magnetic field on intraionic photoluminescence of (Zn,Co)Se

• We roport on magneto-optical properties of (Zn,Co)Se diluted magnetic semiconductor.
• Excitonic photoluminescence reveals efficient energy transfer from band carriers to Co2+ ions.
• Magneto-photoluminescence of Co2+ intraionic transition in ZnSe is presented, characteristic parameters are determined.
• Giant Zeeman effect is used to determine cobalt concentration.

We report on optical properties of epitaxially grown Zn1−xZn1−xCoxSe diluted magnetic semiconductor. Excitonic photoluminescence reveals efficient energy transfer from band carriers to Co2+ ions. Magneto-photoluminescence of 2T1–4A2 intraionic transition of Co2+ in ZnSe is evidenced and discussed based on reported magneto-absorption results. Determined values of g factors are gA=0.62± 0.09 and gB  =3.71± 0.05 for optical transitions, and ge=−0.8±0.2ge=−0.8±0.2 for the 2T1 excited state of Co2+. Cobalt ion concentration in the sample is determined using both reflection measurements of excitonic giant Zeeman effect and direct magnetometry.