Photoinduced non-linear optical monitoring of novel semimagnetic semiconductors Pb1−xYbxX (X = S, Se, Te)

It was revealed that photoinduced non-linear optical methods may be used as a sensitive tool for investigations of low temperature semiconductor-isolator phase transformation. This was experimentally demonstrated using a method of photoinduced optical second harmonic generation, where the photoinducing regime was done by polarized nitrogen laser. The physical insight of the method is explained by the interaction of polarized optical field with boson sub-systems (phonon and magnons) near temperature of the phase transformation. Comparing low temperature dependence of specific heat for Pb1−xYbX (X = S, Se, Te) with the ones for the photoinduced non-linear optical methods we have found substantially better temperature recognition of corresponding phase transformations and the output non-linear optical signal is inversely proportional to the heat capacity renormalized by temperature - Cp / T. The obtained results demonstrate high sensitivity of the photoinduced SHG to the low temperature phase transformations.