Evolution of surface states of antiferromagnetic topological insulator MnBi₂Te₄ with tuning the surface magnetization

Abstract

The interplay between magnetism and topologically non-trivial electronic states is an important subject in condensed matter physics. Recently, the stoichiometric intrinsic magnetic material MnBi2Te4 provides an ideal platform to study the magnetic topological phenomena, such as quantum anomalous Hall effect, axion insulator state, topological magnetoelectric effect. However, it is still controversial whether the topological surface state in the (111) plane is gapped or not. Here, we develop an effective method to study different surface magnetizations based on first-principles calculations. Then we investigate the band dispersions, the Fermi surfaces (FSs), the quasiparticle interferences (QPIs) and the spin texture of topological surface states of MnBi2Te4 with tuning the surface magnetization. We find that the surface magnetization has significant effects on the surface states. Our results also indicate that the symmetry breaking of FSs and QPIs may be a useful way to determine the possible surface magnetization of MnBi2Te4.

Three-Dirac-fermion approach to unexpected universal gapless surface states in van der Waals magnetic topological insulators

“…A previously proposed explanation for the gapless Diraccone surface states is the reconstruction of the surface magnetization, but it will break the three-fold rotation symmetry, resulting in the loss of three-fold rotation symmetry of the surface states [56,65]. In contrast, under the present mechanism of the vdW gap expansion, the gapless surface states retain the original three-fold rotation symmetry.…”

Multiple Magnetic Topological Phases in the van der Waals Crystal Mn(Bi,Sb)4Se7

“…Quantum anomalous Hall effect is also observed in this material . Furthermore, such topological phases, are all strongly coupled to specific magnetic configurations, and thus can be easily tuned and applied to the spintronics devices. − Such novel performance is impossible to be realized in nonmagnetic materials. Following studies unveil that the MnBi 2 Te 4 /(Bi 2 Te 3 ) n ( n = 1, 2, 3) are similar tunable magnetic topological materials. − Topological superconductivity and Majorana edge states were also predicted based on this material family. , …”

On the topological surface states of the intrinsic magnetic topological insulator Mn-Bi-Te family

“…4c ) and AFMx with ferromagnetic in-plane moments (Fig. 4d ), are considered in calculations [ 50 , 69 , 71 , 113 ]. As shown in Fig.…”

“…4d , for A-AFMx, the net magnetic moments break the in-plane rotation symmetry and lead to a TSS constant energy contour with only mirror symmetry. Further consideration of spin texture will result in mirror symmetry breaking [ 113 ]. For G-AFM, the double-sized unit cell in the antiferromagnetic phase may lead to in-plane band folding feature compared to the paramagnetic phase.…”