The X-band (9.3GHz) electron paramagnetic resonance spectra were recorded, at temperatures ranging from ambient to 5K, for 2 samples of symmetry-induced zero band-gap Hg1-xCoxSe (where x was equal to 0.0045 or 0.0087), which had been subjected to electron irradiation. Both materials exhibited, in addition to a narrow intense line (g = 2.018) that was due to a trapped electron/defect center, a broad Co2+ electron paramagnetic resonance line (overlap of the transitions, Ms = 1/2  3/2) which was characterized by g = 2.027 and which disappeared at low temperatures. Only the electron paramagnetic resonance spectra of the sample with the larger concentration of Co ions revealed the presence of an extra electron paramagnetic resonance line with a g-value of 2.024 at temperatures below 40K. However, this line was found in a sample with the lower Co concentration. The extra line was attributed to the Kramers doublet (Ms = 1/2) of the Co2+ ion. The electron paramagnetic resonance data did not indicate the presence of Co3+ ions.

S.K.Misra, J.Pescia, M.Averous, G.Ablart, L.Allam, C.Fau, S.Charar, M.El Kholdi, M.D.Pace: Solid State Communications, 1994, 90[4], 273-6