Crossover from weak-antilocalization transport to quantum magnetoresistance of Dirac states in quenched Fe_0.01Bi₂Te₃ single crystals with large magnetoresistance and high Hall mobility

Magnetotransport properties with a large positive magnetoresistance (MR) and a high carrier mobility for applications have been achieved and probed for quenched Fe_0.01Bi₂Te₃ single crystals. Large positive MR of ∼470% with a Hall mobility of ∼44 000 cm² V⁻¹ s⁻¹ at 5 K and 6 T has been observed on a quenched Fe_0.01Bi₂Te₃ sample, in which the electrical parameters can be tuned by the quenching temperature T _q. The MR behaviors for the quenched samples show a crossover from a weak antilocalization-dominant MR to a linear and non-saturating MR at temperatures of T* ≈ 58−100 K, where the large MR at low temperatures possibly originates from the mechanism of topologically protected backscattering. On the contrary, the MR behaviors for the strain-released sample do not show such a distinct crossover, where only linear-like and non-saturating MR behaviors can be observed. Different electrical transports between the quenched and strain-released samples indicate that the band structure, as well as the surface Dirac electrons in Fe_0.01Bi₂Te₃, can be modified by the lattice strain. Furthermore, it is found that the low-temperature magnetoconductivity can be well described by the weak-antilocalization transport formula, while the high-field linear-like MR at T > T* can be explained in terms of Abrikosov's quantum transport of Dirac-cone states in quenched Fe_0.01Bi₂Te₃ single crystals. (paper)