Magnetic susceptibility of Bi$_{2-x}$Sb$_x$Te$_3$ (0 $<x\le$ 1) crystals in the intrinsic conductivity region

Temperature dependences of the magnetic susceptibility of Bi$_2$Te$_3$–Sb$_2$Te$_3$ with 10, 25, and 50% of Sb$_2$Te$_3$ are experimentally studied using an MPMS MultiVu SQUID magnetometer (Quantum Design, USA) in the temperature range from 2 to 400 K with regard to the anisotropy of the magnetic susceptibility. The behavior of the magnetic susceptibility at temperatures above 250 K is analyzed where the electron system of the crystals passes to the nondegenerate state. It is shown that the temperature dependence of the magnetic susceptibility in the intrinsic conductivity region can be described within the framework of the Pauli and Landau–Peierls approaches.