Spin splitting and disorder of Landau levels in HgTe-based Dirac fermions

This study conducts experimental exploration into a system of two-dimensional Dirac fermions utilizing a critical-thickness HgTe quantum well in weak magnetic fields. The formation and evolution of Shubnikov-de Haas oscillations in the magnetotransport and the capacitive response are studied, complemented by calculations of Landau levels (LLs). It is shown that the behavior of the LLs is influenced not only by the linear dispersion law of the carriers and the Zeeman splitting, but also by the splitting of the Dirac cones in zero magnetic field caused by interface inversion asymmetry. The measured value of the splitting is 1.5 meV. The behavior of the zero LL is studied and its spin splitting is demonstrated. It is shown that the broadening of the zero LL is several times higher than that of the other levels due to the lack of charge impurity screening.