Influence of Mn Concentration on Magnetic Topological Insulator MnxBi2−xTe3 Thin-Film Hall-Effect Sensor

Hall-effect (HE) sensors based on high-quality Mn-doped Bi
₂
Te
₃
topological insulator (TI) thin films have been systematically studied in this paper. Improvement of Hall sensitivity is found after doping the magnetic element Mn into Bi
₂
Te
₃
. The sensors with low Mn concentrations, Mn
_x
Bi
_2-x
Te
₃
, x = 0.01 and 0.08 show the linear behavior of Hall resistance with sensitivity about 5 Ω/T. And their Hall sensitivity shows weak dependence on temperature. For sensors with high Mn concentration (x = 0.23), the Hall resistance with respect to magnetic field shows a hysteretic behavior. Moreover, its sensitivity shows almost eight times as high as that of the HE sensors with low Mn concentration. The highest sensitivity can reach 43 Ω/T at very low magnetic field. This increase of Hall sensitivity is caused by the occurrence of anomalous HE (AHE) after ferromagnetic phase transition. Our work indicates that the magnetic-element-doped TIs with AHE are good candidates for HE sensors.