Influence of carrier concentration and mobility tuned magneto resistance of Bi1−xSbx nanocrystals

In the present work, influence of Sb doping on magneto transport properties of the topological insulator Bi1−xSbx in its nano crystalline form, prepared by microwave assisted solvothermal synthesis, is investigated. At a fixed temperature of 4K, for x=0.06, a positive linear magneto resistance (PLMR) at low magnetic fields was observed, which transforms towards a parabolic classical MR curve with a further increase in Sb molar ratio x. The slope of MR was found to increase with x, the deviation from linearity was found to be attributable to a monotonic decrease in average carrier mobility as well as a systematic increase in the carrier concentration (electron- hole) asymmetry ratio. This elucidates on a possible mechanism for tuning of MR by varying carrier concentration as well as mobility and hence is likely to be instrumental in development of MR dependent devices.