Magnetotransport in thin epitaxial Bi$_{2}$Se$_{3}$ films

The magnetoconductivity of thin Bi$_{2}$Se$_{3}$ films covered by a protective Se layer and grown at (111) BaF$_2$ substrates is studied. It is shown that the negative magnetoconductivity observed at low magnetic fields and caused by the effect of weak antilocalization, as well as the Shubnikov–de Haas oscillations at higher fields, is determined only by the magnetic field component perpendicular to the film plane. The obtained experimental results can be reasonably interpreted under the assumption that the studied films exhibit two-dimensional topologically protected electron states. Moreover, the contribution of these states to the total conductivity turns out to be the dominant one.