Doping with FeSe greatly enhances mobility in topological insulator Bi2Se3 single crystals.

In this paper, we demonstrate a novel strategy to introduce Fe into a Bi 2 Se 3 system through growth of crystals with nominal composition (FeSe) x Bi 2 Se 3. For x < 0.04 , Fe is shown to act mostly as a non-magnetic impurity; it uniformly enters the lattice and monotonically increases the c -lattice parameter, electronic doping level, and Shubnikov–de Haas mobility. The most striking observation is the record high Hall mobility of 8600 cm 2 /V s at 4.2 K for the smallest FeSe content (x = 0.002) that further decreases with x. Elevated mobility is accompanied by a high residual resistance ratio and a rather moderate shift of Shubnikov–de Haas oscillations to a smaller field. These findings indicate that Fe admixture cures the point defects in Bi 2 Se 3 and, thus, opens an effective way to suppress the defect subsystem in Bi 2 Se 3 -based topological insulator materials. [ABSTRACT FROM AUTHOR]