A study of surface electron states in topological insulators (Bi1−xInx)2Se3 with the use of terahertz laser radiation

In this work, we show that the use of terahertz laser radiation combined with magnetic field provides an opportunity to detect high mobility surface electron states in (Bi
_1-x
In
_x
)
₂
Se
₃
solid solutions being either in topological insulator (TI) (x <; 0.05) or trivial semiconductor (TS) (χ > 0.06) phase. It is demonstrated that in TI Bi
₂
Se
₃
the photoelectromagnetic effect amplitude is defined by the number of incident radiation quanta, whereas for TS (Bi
_0.88
In
_0.12
)
₂
Se
₃
it only depends on the power of a laser pulse irrespective of its wavelength. The possible reasons for such a different behavior may be related to the enhanced thermalization time of the non-equilibrium carriers due to strong damping of electron-electron interaction in TI.