Birefringence of Cu2ZnSiSe4 single crystals

Abstract

In Cu2ZnSiSe4 single crystals an interference spectra of the Fabry–Perot type due to observed birefringence were studied and spectral dependence of the refractive index n|| (E||c) and n⊥ (E⊥c), which intersect at isotropic wavelength λ0=622nm (300K) and 605nm (10K) were defined. The spectral dependence of Δn=n⊥–n|| in the short-wave and long-wave side of the wavelength λ0 was determined. It was found that when λ>λ0 Δn is negative and when λ<λ0 Δn is positive. Wavelength λ0 shifts as the temperature decreases toward shorter wavelengths. Phases of the n|| and n⊥ light waves in λ>λ0 and λ<λ0 are different. At a wavelength of 538nm (10K) Δn has a maximum. Absorption coefficient in the fringes varies up to 102–103 times.