Non-linear optical effects and transport phenomena of magnetic semiconductors Pb_1−xPr_xTe near the semiconductor–metal phase transformation

Abstract

Measurements of transport and non-linear optical (NLO) properties of the new, synthesized semiconductor Pb0.9835Pr0.0165Te in the vicinity of low-temperature metal–semiconductor phase transformations were performed. A correlation between the temperature behaviour of transport properties near the phase transition and NLO susceptibilities of second- and third-order was observed. FTIR spectra show the substantial role played by the Pr3+ localized levels in the observed anomalies.Among the transport properties, the resistivity, Seebeck coefficient and specific heat were measured. The presence of the minimum at about in the temperature dependence of the resistivity ρ(T) is due to the metal–semiconductor transition in Pb1−xPrxTe and the low-temperature upturn observed in the resistivity is well fitted by the Mott law. Substitution of PbTe by other rare earths shows the crucial role played by Pr in the observed dependences.Experimental temperature measurements using photo-induced NLO (pumped by a UV-laser as well as by second harmonics of the YAG–Nd lasers) and a probing YAG–Nd (at λ = 1.06 µm) laser, show the existence of two maxima in the photo-induced second harmonic generation (PISHG) at temperatures 17 and 30 K, the behaviours of which substantially depend on the wavelength of the pump beam. At the same time the third-order two-photon absorption possesses maxima near 50 K, i.e. at about . Such discrepancies in the positions of the temperature maxima are caused by the difference in contributions of the photo-induced anharmonic phonons near the surfaces PISHG and the bulk. Varying the penetration depth of the photo-inducing light one can operate with the output NLO properties.

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

“…TPA measurements have established that the Pb 1−x Pr x Te (x = 1.65%) possess higher TPA value if compared to the Gdcontaining compounds, with a maximum around 50 K corresponding to the temperature of metal-semiconductor transition observed in the temperature behavior of the resistivity [16].…”

Emergence of half metallicity in Cr-doped GaP dilute magnetic semiconductor compound within solubility limit

“…These materials present promising candidature for spintronic devices due to their peculiar property of utilizing both, charge and spin of electrons to create new functionalities beyond conventional semiconductors. Moreover, these materials are also very important for nonlinear optics [1,2]. The concept of half metallicity was firstly formulated by de Groot et al [3] in semi Heusler alloy, NiMnSb in terms of spin polarization.…”

Optical and thermal tools for the phase transitions detection in the guanidine compounds

“…Due to this reason the optical and especially nonlinear optical methods become more and more popular for detection of different phase transitions [5,6]. The higher order optical effects are more sensitive than this of lower order a two-photon absorption and a third harmonics generation [7]. However, there is a strong shortcoming for the third harmonic generation: a dozens of samples, including semiconductors and even dielectrics, are nontransparent for the tripled frequency wavelengths.…”