Influence of electric current and magnetic field on terahertz photoconductivity in Pb$_{1-x}$Sn$_x$Te(In)

Photoconductivity of Pb$_{1-x}$Sn$_x$Te(In) solid solutions in the terahertz spectral range is defined by a new type of local electron states linked to the quasi-Fermi level. The paper deals with investigation of the influence of electric current and magnetic field on the amplitude of the terahertz photoconductivity in Pb$_{1-x}$Sn$_x$Te(In) alloys of different composition. It is shown that the density of local electron states responsible for the positive persistent photoconductivity decreases with increasing electric current via a sample, as well as with transition to the hole conductivity in samples with a high content of tin telluride ($x > 0.26$). It is found that the magnetic field dependence of the positive photoconductivity is non-monotonous and has a maximum. The maximum position in magnetic field is proportional to the terahertz radiation quantum energy. Mechanisms responsible for the effects observed are discussed.