Fig. 4: Topological phase diagram of MnBi₄Te₇ as a function of temperature and out-of-plane magnetic field across the antiferromagnetic transition.

The colored map is based on Nernst measurements in Fig. 2 and the black/green dashed lines indicate the magnetic transitions reported in magnetic measurements in ref. ⁵. The AFM phase for vanishing magnetic fields is linked to a 3D TI state, although one needs to shift the Fermi level into the bulk gap to access the protected surface states. The fully spin-polarized phase is linked to the Weyl cones, detected by the ANE. As an inset, there is a sketch of the bulk bands adapted from ref. ⁵ (see text for details).