Electronic structure of magnetic topological insulators Mn(Bi$_{1-x}$Sb$_{x})_2$Te$_4$ with various concentration of sb atoms

Intrinsic magnetic topological insulator MnBi$_2$Te$_4$ provides a promising platform to implement the quantum anomalous Hall effect at increased temperatures and other unique topological effects. However, to do this, the energy gap opening at the Dirac point should be located at the Fermi level. One of the widely used methods to shift the Dirac point toward the Fermi level is the partial substitution of Bi atoms for Sb atoms. In this work, the electronic structure of the core levels and valence band of Mn(Bi$_{1-x}$Sb$_{x})_2$Te$_4$ compounds with various concentration $x$ of Sb atoms from $0$ to $1$ has been studied. It has been shown that the Dirac point with an increase in the concentration of Sb atoms is shifted toward the Fermi level and becomes localized at it when $x = 0.3$. In this case, the “rigid” shift of the valence band, including the Mn $3d$ level, has been observed without changes in the structure of the valence and conduction bands. The concentration dependence of the shift of the Dirac point is approximated by a square root function, which corresponds to a linear increase in the charge carrier density.