Momentum-inversion symmetry breaking on the Fermi surface of magnetic topological insulators

Magnetic topological insulators (MnBi2Te4)(Bi2Te3)(n) were anticipated to exhibit magnetic energy gaps, while recent spectroscopic studies did not observe them. Thus, magnetism on the surface is under debate. In this work, we propose another symmetry criterion to probe surface magnetism. Because of both time-reversal symmetry breaking and inversion symmetry breaking, we demonstrate that the surface band structure violates momentuminversion symmetry and leads to a threefold rather than sixfold rotational symmetry on the Fermi surface if corresponding surface states couple strongly to the surface magnetism. Such a momentum-inversion symmetry violation is significant along the Gamma - K direction for surface bands on the (0001) plane, which serves as a criterion for determining the surface magnetism.

Automated summary

In this study, another symmetry criterion is proposed to investigate the existence of surface magnetism in magnetic topological insulators. The research demonstrates that the surface band structure exhibits a threefold rotational symmetry on the Fermi surface when time-reversal and inversion symmetry are broken, serving as an important criterion for determining surface magnetism.