Transport and nonlinear optical study of semimagnetic phase transitions in ternary alloys Pb1−xRxTe (R = Pr3+, Gd3+)

Transport and nonlinear optical features of magnetic semiconductors Pb1−xRxTe (R = Pr3+, Gd3+ at x = 1.00 and 5.00%) are investigated. It is shown that third order nonlinear optical methods, particularly two-photon absorption described by fourth rank polar tensors may be used as a sensitive and partially complimentary tool for investigation of the semiconductor–insulator phase transformation. The presence of a minimum of resistivity in Pb1−xPrxTe at about Tρmin = 50 K in the temperature dependence of the resistivity ρ(T) is caused by metal–semiconductor origin of the phase transition. Particularly with nearing to the phase transition temperature, one can observe an increase of effective two-photon oscillator strengths. Principal role in the observed phenomenon play anharmonic electron–phonon interactions, what is independently shown using temperature dependent photoinduced SHG.