Jahn–Teller effect in Co2+-doped SrLaGa3O7

Abstract

We present here spectroscopic investigations of the Co2+ in SrLaGa3O7. Single crystals of SrLaGa3O7 have been grown by the Czochralski method in a nitrogen atmosphere. The absorption spectra were taken at various temperatures from 15 to 300 K in the spectral range 190–2500 nm. It has been found that the Co2+ ions substitute octahedrally coordinated Sr2+ in the material. We have estimated the quantities of the crystal field parameter 10 Dq, Racach parameters B and C and spin-orbit coupling. For consideration of the absorption lineshape we have taken into account the coupling of localised electrons to the symmetrical a1 mode and Jahn–Teller coupling of the T⊗ε and T⊗τ types. Absorption line shape has been reproduced considering the Fano anti-resonance of the broad band related to the 4T1→4T1 transitions with sharp 2T1, 2T2, and 2T1 states.