Disorder-dominated non-saturating linear magnetoresistance in Sr-doped Bi2Se3 thin films

Sr_xBi₂Se₃ thin films was known as a candidate of topological superconductor. We report that the Linear Magnetoresistance (LMR) of Sr_xBi₂Se₃ films originates from mobility fluctuation induced by disorder, rather than the gapless linear energy dispersion emphasized by Abrikosov’s quantum model. We also find the transition of disorder parameters from average mobility 〈μ〉to the width of mobility disorder △μ, indicting by 1/K_Fl where l is the mean free path and K_F is the fermi wave factor, from Sr_0.025Bi₂Se₃ to Sr_0.085Bi₂Se₃. It demonstrates the dramatic decline in film mobility caused by slight increase in doping concentration x. The film was prepared by Molecular Beam Epitaxy (MBE) on Al₂O₃(0001) substrate with doping concentrations x from 0.025 to 0.125, and the LMR is still not saturated at 14 Tesla. For comparison, we also systematically studied Mn_xBi₂Se₃ films and showed similar results.