Role of phonon subsystems in second order optical effects in semiconductor semimagnetic Pb_(1-x)R_xX (R=Pr, Yb and X=S, Se, Te)

摘要

Measurements of transport and non-linear optical properties in magnetic semiconductors Pb_(1-x)R_xX (R=Pr, Yb and X=S, Se, Te at x≈1-3%) were performed to elucidate an influence of magnetic ions on behavior of the charge carriers. It was shown that nonlinear optical methods may be used as a sensitive tool for investigation of electron-phonon an harmonicity near the low temperature semiconductor isolator phase transformation. The presence of the minimum in Pb_(1-x)Pr_xTe at about T_(min)~ρ = 50 K in the temperature dependence of the resistivity ρ(T) is due to metal-semiconductor transition. Particularly with increasing of electron-phonon interactions indicated by temperature dependent Debye term (parameter β), one can observe an increase of two-photon oscillator strengths.