Topological driven linear magnetoresistance in Sb-doped MnBi₂Te₄

Linear magnetoresistance (LMR) is an attractive phenomenon that shows potential for uncovering novel physics and gauss sensor applications. Here we report a Fermi-level-sensitive LMR by doping Sb into antiferromagnetic topological insulator (TI) MnBi2Te4 crystals. The LMR is most remarkable when the Fermi level is close to the charge neutral point and the bulk carriers are largely suppressed. Our detailed analyses reveal that the slope of the LMR shows linear dependence on the inverse of carrier density. The results are quantitatively consistent with the quantum LMR model based on the surface state of a TI and thus reveal a transport signature of the topological surface state. Our work provides crucial insights into the understanding of the essential MR behavior and the surface state in MnBi2Te4.