Figure 3. Surface g-factor measurement on Bi₂Se₃.

(a) Potential landscape of Bi₂Se₃ obtained by mapping E₀ at 11 T showing a potential minimum. The centre of the potential minimum is determined by the 2D parabolic potential fitting and is marked as a cross. The scale bar corresponds to 10 nm. Measurement conditions: V_s=50 mV, I_t=50 pA, V_mod=2.8 mV_rms and T=1.5 K. (b) Tunnelling spectra taken at the potential minimum centre at fields from 3 to 11 T with 1 T intervals. The spectra have been shifted for clarity. Measurement conditions: V_s=−220 mV, I_t=100 pA, V_mod=1.4 mV_rms and T=1.5 K. (c) E₀ at different B obtained by fitting the data of b with a Lorentz line shape and plotted with black symbols (left axis). The error bars are the standard deviation of the fitting analysis. The effects of the potential and the non-ideal dispersions on the LL₀ energies are represented by and , respectively. Their influences can be excluded by subtracting their contributions. The red symbols denote the LL₀ energies after subtracting the effect of the potential (E₀−E_V). The blue symbols correspond to the LL₀ energies after subtracting the effects from both the potential and the non-ideal dispersions () (right axis, in the relative energy scale). The black curve denotes the fitting to E₀ with B according to equation (2). The red and blue lines show the linear fitting of E₀−E_V and with B, respectively. (d–f) Similar data and analysis as a–c for a potential maximum of Bi₂Se₃. Measurement conditions of d and e: V_s=−200 mV, I_t=165 pA, V_mod=1.8 mV_rms and T=1.5 K.