Doping-enhanced robustness of anomaly-related magnetoresistance in WTe _{2± α} flakes

We study systematically the negative magnetoresistance ( MR) effect in WTe _{2± α} flakes with different thicknesses and doping concentrations. The negative MR is sensitive to the relative orientation between electrical-/magnetic-field and crystallographic orientation of WTe _{2± α} . The analysis proves that the negative MR originates from chiral anomaly and is anisotropic. Maximum entropy mobility spectrum is used to analyze the electron and hole concentrations in the flake samples. It is found that the negative MR observed in WTe _{2± α} flakes with low doping concentration is small, and the high doping concentration is large. The doping-induced disorder obviously inhibits the positive MR, so the negative MR can be more easily observed. In a word, we introduce disorder to suppress positive MR by doping, and successfully obtain the negative MR in WTe _{2± α} flakes with different thicknesses and doping concentrations, which indicates that the chiral anomaly effect in WTe ₂ is robust.