Zeeman splitting of the conduction band of HgTe quantum wells with a semimetallic spectrum

Shubnikov-de Haas oscillations in Hg$_{1-x}$Cd$_x$Te/HgTe/Hg$_{1-x}$Cd$_x$Te structures with the widths of a well of $16$ and $20$ nm have been investigated in tilted magnetic fields. The spin-to-orbital splitting ratio in the conduction band has been found in a wide range of electron densities. The magnitude and density dependence of the ratio agree fairly well with the calculations of the spectrum in the $8$-band $kP$ model. It has been shown that the effective $g$ factor is anisotropic, $g_\parallel<g_\perp$. The anisotropy is very high at low densities but decreases rapidly with an increase in the density, approaching unity at $n_e=(3-4)\times10^{11}$ cm$^{-2}$.