Gate-contolled linear magnetoresistane in thin Bi_2Se_3 sheets

Gao, B.F. [Max Planck Institute for Solid State Research] Gehring, Pascal [UCL] Burghard, M. [Max Planck Institute for Solid State Research] Kern, K. [Max Planck Institute for Solid State Research]

We explore the emergence of linear magnetoresistance in thin Bi_2Se_3 sheets upon tuning the carrier density using a back gate. With increasingly negative gate voltage, a pronounced magnetoresistance of ~100% is observed, while the associated B-field dependence changes from quadratic to linear. Concomitantly, the resistance-versus-temperature curves evolve from metallic to semiconductor-like, and increasingly strong weak anti-localization behavior is manifested. Analysis of the magnetoresistance data reveals two contributions, namely from the bulk conduction band and from a state inside the bulk gap. The latter is responsible for the linear magnetoresistance and likely represents the topologically protected surface state.