Figure 4. WAL effect studied on 20 QLs Bi₂Se₃, 20 QLs Bi₂Te₃ and 1 QL Bi₂Se₃/19 QLs Bi₂Te₃ films.

(a)–(c) Normalized MR of 20 QLs Bi₂Se₃, 20 QLs Bi₂Te₃ and 1 QL Bi₂Se₃/19 QLs Bi₂Te₃ in the low field at different temperatures. (d)–(f) Fitted curves (solid red lines) with Eq. (1) are shown in 20 QLs Bi₂Se₃, 20 QLs Bi₂Te₃ and 1 QL Bi₂Se₃/19 QLs Bi₂Te₃ in perpendicular field at T = 4 K respectively. For the 20 QLs Bi₂Se₃ film and the 1 QL Bi₂Se₃/19 QLs Bi₂Te₃ film, the fitting range is from 2.5 kOe to −2.5 kOe. However, for the 20 QLs Bi₂Te₃ film, the WAL dip is small that the fitting range is from 1 kOe to −1 kOe. (g)–(i) MR as a function of the normal H component with the θ = 90° MR subtracted for 20 QLs Bi₂Se₃, 20 QLs Bi₂Te₃ and 1 QL Bi₂Se₃/19 QLs Bi₂Se₃ at θ equals to 0°, 45°, 60°, 80°. The inset shows the rotation configuration. (j)–(l) Violet symbols are the T = 4 K magneto conductance for the 20 QLs Bi₂Se₃ film (j), the 20 QLs Bi₂Te₃ film (k) and the 1 QL Bi₂Se₃/19 QLs Bi₂Te₃ film (l) after subtracting the 3D WAL effect. The solid red lines show the fitting results with Eq. (1). Compared with corresponding figure (d) to (f), all the phase coherence lengths of our TI films become larger after subtracting the 3D WAL effect.