Electron Spin Resonance of Cr²⁺ in Cadmium Sulfide Single Crystals

Electron spin resonance of Cr 2+ in cadmium sulfide single crystals has been studied at liquid helium temperature range and X-band. The observed spectra consist of six main lines having anisotropic g -values. They are interpreted in terms of a Jahn-Teller distortion of Cr 2+ ion in directions nearly bisecting the lines to the nearest sulfur neighbors. There are such six directions in the crystal. The effective spin Hamiltonian appropriate to explain the results obtained at 1.4°K is {aligned} Heff{=}g'//β HzSz+ Sₓ, {aligned} where g ' // =7.75±0.03, g ' ⊥ ∼0, Δ =0.150±0.002 cm -1 , and S =1/2, and the z -axis makes an angle of 57°45' with the c -axis in the (1120) plane or its equivalent planes, which coincides with the direction along which the Jahn-Teller distortion takes place. Resolved hyperfine interaction is observed with Cd 111 and Cd 113 , whose hyperfine splitting constant is (2.1±0.1)×10 -3 cm -1 . The results are compared with the work of Estle, Walters, and deWit. A photosensitive spin resonance line has been observed at 1.7°K under visible light illumination.