Superconducting properties of single crystal wires of lead telluride doped with thallium active pore materials based on sludges of Cr-Ni alloy electrochemical machining

Abstract

Results of the measurements of temperature dependences of resistivity of thin single crystal wires of PbTe in the temperature region 0.4 ÷ 4.2 K are presented. Thallium average concentration was 0.001 ÷ 0.02 at.%. Single crystal wires (with diameters d = 5 ÷ 100 μm) were obtained by filling of quartz capillary with the solution melt with the following directed crystallization of this material. The structural perfection of investigated samples was tested by X-ray diffraction and LAMMA analysis. It is revealed, that at low temperatures in single crystal wires of PbTe transition in a superconducting state is observed. The temperature of transition correlates with impurity concentration (for single crystal wires of PbTe at thallium concentration 2% Tc=2,1K). Mechanisms leading to superconducting transition and features of temperature dependence of resistance in the field of previous transition are discussed. The interpretation of the obtained results is given based on model of an impurity with skipped valence.