From linear magnetoresistance to parabolic magnetoresistance in Cu and Cr-doped topological insulator Bi2Se3 films

Abstract

We report on the magnetotransport properties of Cu- and Cr-doped topological insulator Bi2Se3 films grown on silicon (100) substrate by chemical vapor deposition. Upon doping of non-magnetic Cu, Bi2Se3 film's carrier density is reduced and the magnetoresistance changes from a strong positive parabolic magnetoresistance to a linear magnetoresistance. This linear magnetoresistance is similar to the linear magnetoresistance in other gapless topological states of matter and has a strong temperature dependence. In contrast, the magnetoresistance of Cr-doped Bi2Se3 films remains to be parabolic and becomes temperature independent upon increased Cr-doping. These results suggest that the absence of linear magnetoresistance in Cr-doped Bi2Se3 is related to the magnetic dopants that induce time reversal symmetry breaking and surface states gap opening.