Quantum interference phenomena and electron - electron interaction in topological insulator Bi₂Se₃ thin polycrystalline films

The temperature (T = 2.0 - 300 K) and magnetic field (B = 0 - 14 T) dependences of the transport coefficients were obtained for the topological insulator (TI) polycrystalline Bi2Se3 films with thicknesses d = 40 and 200 nm grown on glass substrates by thermal evaporation in vacuum from a single source. In the region of weak magnetic fields, a sharp increase in magnetoresistance (MR) with increasing B was observed, indicating the presence of the weak antilocalization (WAL) effect, which is typical for 3D-TIs. However, the longitudinal resistance R-xx in-creases logarithmically with decreasing temperature below certain temperature T-c, which is not characteristic of the WAL effect in 2D-structures and indicates possible existence of the so-called "transport paradox ". In the temperature dependences of the Hall resistance, Hall coefficient and MR we also registered clearly pronounced kinks near T-c. The R-xx(T) dependence for a 40 nm film, with decreasing temperature in addition to the R-xx minimum near T-c, exhibits a maximum near 2.1 K. Estimates of the number of independent transport channels m and the dephasing length l(phi) show that as d increases from 40 nm to 200 nm, m increases from 1 to 3, while l(phi) changes insignificantly. The nonmonotonic behavior of the T- and B- dependences of the kinetic coefficients, the occurrence of the "transport paradox " are associated with a change in the contributions of WAL and electron-electron interaction effects when the nature and magnitude of the external influence and film thickness change. It follows from the data obtained that not only in very thin monocrystalline films, but also in rather thick polycrystalline Bi2Se3 films prepared by the simple method of the thermal evaporation in vacuum on amorphous substrates, quantum interference effects and "transport paradox " can be manifested.