Monopolar photoelectromagnetic effect in Pb_(1-x)Sn_xTe(In) under terahertz laser radiation

摘要

We report on the observation of a new effect-the appearance of a galvanic signal in the narrow-gap semiconductor Pb_(1-x)Sn_xTe(In) in the magnetic field under the action of strong 100 ns-long terahertz laser pulses. The signal changes its sign and kinetics as the temperature increases from 4.2 K to 25 K. This semiconductor possesses inversion symmetry of the crystalline lattice making impossible the observation of the magnetophotogalvanic effect which looks similar in its experimental manifestation. On the other hand, the laser quantum energy is much less than the bandgap of the semiconductor making the effect considerably different from the conventional Kikoin-Noskov photoelectromagnetic effect. Possible mechanisms responsible for the appearance of the effect are discussed.