Magnetic and electrical transport study of the intrinsic magnetic topological insulator MnBi2Te4 with Ge doping

As an intrinsic magnetic topological insulator with magnetic order and non-trivial topological structure, MnBi₂Te₄ is an ideal material for studying exotic topological states such as quantum anomalous Hall effect and topological axion insulating states. Here, we carry out magnetic and electrical transport measurements on (Mn_1−xGe_x)Bi₂Te₄ (x = 0, 0.15, 0.30, 0.45, 0.60, and 0.75) single crystals. It is found that with increasing x, the dilution of magnetic moments gradually weakens the antiferromagnetic exchange interaction. Moreover, Ge doping reduces the critical field of ferromagnetic ordering, which may provide a possible way to implement the quantum anomalous Hall effect at lower magnetic field. Electrical transport measurements suggest that electrons are the dominant charge carriers, and the carrier density increases with the Ge doping ratio. Additionally, the Kondo effect is observed in the samples with x = 0.45, 0.60, and 0.75. Our results suggest that doping germanium is a viable way to tune the magnetic and electrical transport properties of MnBi₂Te₄, opening up the possibility of future applications in magnetic topological insulators.