The magneto-transport properties of Bi2Se3–ySy were investigated. Magnetoresistance (MR) decreases with an increase in the S content, and finally, for 7% (i.e., y = 0.21) S doping, the magnetoresistance becomes negative. This negative MR is unusual as it is observed when a magnetic field is applied in the perpendicular direction to the plane of the sample. The magneto-transport behavior shows the Shubnikov–de Haas (SdH) oscillation, indicating the coexistence of surface and bulk states. The negative MR has been attributed to the non-trivial bulk conduction.

中文翻译：

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Bi2Se3-ySy 拓扑绝缘体在垂直磁场下的异常负磁阻

研究了 Bi2Se3-ySy 的磁传输特性。磁阻 (MR) 随着 S 含量的增加而降低，最后，对于 7%（即 y = 0.21）的 S 掺杂，磁阻变为负值。这种负 MR 是不寻常的，因为它是在垂直于样品平面的方向施加磁场时观察到的。磁传输行为显示 Shubnikov-de Haas (SdH) 振荡，表明表面态和体态共存。负 MR 归因于非平凡的体传导。