Coexistence of surface and bulk state and negative magnetoresistance in Sulfur doped Bi2Se3

The magneto-transport properties in Sulfur doped Bi2Se3 are investigated. The magnetoresistance (MR) decreases with increase of 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 magnetic field is applied with the perpendicular direction to the plane of the sample. The magneto-transport behavior shows the shubnikov-de hass (SdH) oscillation indicating the coexistence of both surface and bulk states. The negative MR has been attributed to the bulk conduction.