Influence of Mn concentration on magnetic topological insulator MnxBi2−xTe3 thin film Hall effect sensor

Hall effect sensors are used widely in areas including position sensing, DC current transformers, and fuel level indicator due to their low costs, high reliability, free of contact bounce, and immune to environmental contaminants [1]. However, the lower measuring accuracy and sensitivity comparing to fluxgate magnetometers limit their application. Improving the sensitivity becomes a crucial issue for Hall effect sensor. The key factor determining sensitivity of Hall effect sensor is high electron mobility. Therefore, GaAs and InAs are often used [2]. Recently, topological insulators (TIs) are discovered with an ultra-high surface conductivity [3]. Unlike normal semiconductor, TIs have gapless surface states, protected by time reversal symmetry, inside the bulk band gap, which prohibits the backscattering on non-magnetic impurities. The surface state of TIs can be broken by introducing magnetic impurities. Magnetic impurities lead to a small surface band gap which can induce phenomena such as the quantum anomalous Hall effect (AHE) [4]. All above features enable TIs suitable materials for developing Hall effect sensor with ultra-high sensitivity. In this work, we investigated the Hall effect sensor fabricated by Mn-doped Bi₂Te₃. AHE was found in Mn_xBi_2-xTe₃ material with high Mn concentration. The sensitivity of Mn_xBi_2-xTe₃ Hall effect sensor with different Mn concentration will be discussed.