Non-resonant absorption of the X-band electromagnetic wave power in a narrow-gap PbS semiconductor at temperatures of 2.6–8 K in the range of magnetic fields 0–100 mT

Studies of magnetically dependent effects of nonresonant absorption of electromagnetic wave energy in the resonator of the X-band EPR spectrometer related to the superconductivity of metallic lead inclusions and microscopic structural defects in crystals of narrow-band semiconductors PbS_{1 – x} and PbS_{1 – x}:Mn have been performed. It is shown that nanoscale lead particles present in polycrystalline material PbS_0.96 with a high content of sulfur vacancies at temperatures of 2.6–8 K manifest themselves as superconductors of the 2nd kind and demonstrate high thermomagnetic stability. It was found that in a single-crystal sample PbS_0.996 with a significantly lower concentration of sulfur vacancies under the influence of the electric component of the microwave field in the resonator of the ESR spectrometer, non-periodic bursts of microwave power absorption associated with avalanches of Abrikosov vortices and demonstrating the absence of thermomagnetic stability of superconducting regions associated with defects in the crystal structure of the sample PbS_0.996 are observed.