This study presents a systematic investigation of ${\mathrm{Mn}}_{1-x}{\mathrm{Pb}}_x{\left({\mathrm{Bi}}_{1-y}{\mathrm{Sb}}_y\right)}_2{\mathrm{Te}}_4$ crystals over a wide range of concentrations ($x$ = 10–60%, $y$ = 5–60%). It was found that the value of the bulk band gap is determined exclusively by the Pb concentration and it closes upon approaching Pb 40–50 %, which is consistent with the topological phase transition predicted for this system. The position of the Dirac point is determined by the Pb/Sb ratio, rather than the absolute Sb content. The magnetic properties depend on the dilution of the Mn sublattice by Pb and are less sensitive to Sb. We show that the simultaneous substitution of Mn and Bi allows independent control of the topological phase and the position of the Fermi level.

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• Topological materials