Extended Data Fig. 10: Chern number tuned by controlling the thickness of the middle magnetic TI layer.
From: Tuning the Chern number in quantum anomalous Hall insulators
a–d, Dependence of ρxx (red) and ρyx (blue) on μ0H for the m = 2 sample, with different middle magnetic TI layer thicknesses d. All measurements were taken at the charge-neutral point (Vg = Vg,0) and T = 25 mK. ρyx(0) displays the quantized values of 0.995h/e2, 0.996h/e2, 0.469h/e2, 0.498h/e2 and 0.490h/e2 for the samples with d = 0, 1, 2, 3 and 4, respectively. The corresponding ρxx(0) values are 0.0001h/e2, 0.0009h/e2, 0.089h/e2, 0.008h/e2 and 0.024h/e2. e–h, Dependence of ρyx(0) (blue squares) and ρxx(0) (red circles) on gate voltage (Vg − Vg,0) for d = 0, 1, 2, 3 and 4. All measurements were taken at T = 25 mK and μ0H = 0 T after magnetic training. Because the d = 2 sample is near the topological phase transition regime and therefore has a smaller hybridization gap (Fig. 4d), it has a larger ρxx. For the d = 4 sample, the larger ρxx is probably induced by the enhanced dissipative quasi-helical side surface states and/or residual bulk carriers with increasing sample thickness.
