Landau level spectroscopy of the PbSnSe topological crystalline insulator

We report on an infrared magnetospectroscopy study of ${\mathrm{Pb}}_{1\ensuremath{-}x}{\mathrm{Sn}}_{x}\mathrm{Se}$, a topological crystalline insulator. have examined set samples, all in the inverted regime electronic bands, with tin composition varying from $x=0.2$ to 0.33. Our analysis shows that observed response, composed series interband inter-Landau-level excitations, can be interpreted and modeled using relativistic-like Hamiltonian for three-dimensional massive Dirac electrons, expanded include diagonal quadratic terms impose band inversion. In our data, we not found any clear signature massless electron states are present surface ${\mathrm{Pb}}_{1\ensuremath{-}x}{\mathrm{Sn}}_{x}\mathrm{Se}$ crystals regime. Reasons this unexpected result discussed.