Modification of Shubnikov-de Haas oscillation and quantum Hall effect for Bi2Se3 crystals by Fe

Shubnikov-de Haas (SdH) oscillations and the quantum Hall effect (QHE) can give insights into quantum oscillations of charge carriers. We report the SdH oscillations and QHE of magnetically doped topological insulator FexBi2-xSe3 crystals, in which the lattice constant c decreases with the increasing dopant concentration but increases when x is greater than 0.08. From the fitting of low-temperature magnetoresistance data to the Lifshitz-Kosevich formula, the effective mass of the carriers and the Dingle temperature of the samples were extracted and show a similar trend of change as the lattice constant. A constant step size of 1/R-xy observed during Hall measurements at low temperatures implies two-dimensional-like transport behavior associated with the layered structure of the doped Bi2Se3 samples. Two-dimensional and three-dimensional charge carrier densities were calculated, and the latter had a similar trend of change as the lattice constant. A systematic study of the changes in all these properties with increasing dopant concentration suggests that they are highly correlated.