Figure 5

(a) Bulk and (b) edge energy dispersions for the nominal experimental parameters of the triple quantum well, i.e., \(d_0 = 6.7\) nm and \(t=3.0\) nm, which falls close to the phase transition line, shaded rectangle in Fig. 2b. The lines and colors follow the same definitions as in Fig. 3. The system is in phase I, with the \(E_1^0\) and \(H_1^0\) subbands hybridized with nearly vanishing mass \({\tilde{M}}_0\), yielding a linear pair of Dirac subbands (all the subbands are spin-degenerate). (c) The Fourier transform of the measured Shubnikov-de Haas oscillations show two main peaks splitting with increasing \(V_g\) and a further Rashba-like splitting at high \(V_g\). (d) The theoretical SdH frequencies F for the linear and parabolic subbands from panel (a) qualitatively matches the experimental measurements. In both (c) and (d), the dashed lines mark \(F_j(E_F)\) for each subband with \(E>0\) from panel (a) and the peaks are built from gaussian broadenings for easy comparison with panel (c).