Magnetoresistance oscillations in films of multicomponent topological insulators based on bismuth telluride

In layered films of $n$-(Bi, Sb, In)$_2$(Te, Se)$_3$ solid solutions, which are 3D topological insulators, quantum oscillations and temperature dependences of magnetoresistivity have been investigated in strong magnetic fields up to 14 T. Using the Lifshitz–Kosevich theory, the parameters of the surface states of Dirac fermions have been calculated, revealing that the studied films are characterized by two cyclotron resonance frequencies. It is demonstrated that the surface concentration of Dirac fermions increases in films with a high thermoelectric power factor when substituting atoms in the Bi sublattice with In, compared to Sb $\to$ Bi substitutions. The Landau level indices and Berry phase have been calculated. It is demonstrated that with an increase in the cyclotron resonance frequency in the film $n$-Bi$_{1.92}$In$_{0.02}$Te$_{2.88}$Se$_{0.12}$, Landau levels are observed at higher magnetic fields compared to $n$-Bi$_{1.6}$Sb$_{0.4}$Te$_{2.91}$Se$_{0.09}$. In the $n$-Bi$_{1.6}$Sb$_{0.4}$Te$_{2.91}$Se$_{0.09}$ films, temperature dependencies of resistivity in the magnetic field $B$=14 T exhibit plateaus at low temperatures, characteristic of topological insulators. At temperatures below 15 K, a non-linear dependence of resistivity on magnetic field is observed due to quantum interference effects associated with weak anti-localization of Dirac fermions.