Abstract
The recent discovered intrinsic magnetic topological insulator MnBi2Te4 have been met with unusual success in hosting emergent phenomena such as the quantum anomalous Hall effect and the axion insulator states. However, the surface-bulk correspondence of the Mn-Bi-Te family, composed by the superlattice-like MnBi2Te4/(Bi2Te3)n (n = 0, 1, 2, 3 ...) layered structure, remains intriguing but elusive. Here, by using scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES) techniques, we unambiguously assign the two distinct surface states of MnBi4Te7 (n = 1) to the quintuple-layer (QL) Bi2Te3 termination and the septuple-layer (SL) MnBi2Te4 termination, respectively. A comparison of the experimental observations with theoretical calculations reveals the diverging topological behaviors, especially the hybridization effect between magnetic and nonmagnetic layers, on the two terminations: a gap on the QL termination originating from the topological surface states of the QL hybridizing with the bands of the beneath SL, and a gapless Dirac-cone band structure on the SL termination with time-reversal symmetry. The quasi-particle interference patterns further confirm the topological nature of the surface states for both terminations, continuing far above the Fermi energy. The QL termination carries a spin-helical Dirac state with hexagonal warping, while at the SL termination, a strongly canted helical state from the surface lies between a pair of Rashba-split states from its neighboring layer. Our work elucidates an unprecedented hybridization effect between the building blocks of the topological surface states, and also reveals the termination-dependent time-reversal symmetry breaking in a magnetic topological insulator, rendering an ideal platform to realize the half-integer quantum Hall effect and relevant quantum phenomena.
Highlights
The recently discovered intrinsic magnetic topological insulator MnBi2Te4 has been met with unusual success in hosting emergent phenomena such as the quantum anomalous Hall effect and the axion insulator states
We identify a gap on the QL termination, originating from the hybridization between the topological surface states of the QL and the bands of the SL beneath, and a gapless Dirac-cone band structure on the SL termination with time-reversal symmetry
A gapless Dirac electronic structure is observed on the SL termination, whereas the QL termination is found to be gapped because of the hybridization between different orbitals of the neighboring topological insulator (TI) building blocks, implying different surface magnetism on the two terminations
Summary
The recent discovery of the intrinsic magnetic topological insulator MnBi2Te4 and its derivatives MnBi2Te4=ðBi2Te3Þn (n 1⁄4 1;2;...), comprising alternating. Surface-bulk correspondence is generally considered to be the unifying feature relating the topology of the bulk bands to the surface states in topological materials [26] This correspondence is intriguing in the superlatticelike MnBi2Te4=ðBi2Te3Þn layered structure for n ≥ 1, where the hybrid structure creates distinct electronic structures on separate terminations due to the interplay of topology and magnetism at the interfaces of magnetic TI (MnBi2Te4) and nonmagnetic TI (Bi2Te3) layers. Bands shows a pair of Rashba-like splitting bands from the QL underneath and a strongly warped band from the SL, the hybridization of which contributes to the flower-shaped QPI patterns Our findings of such diverging topological behaviors on the two terminations of MnBi4Te7 strongly rely on the hybridization of bands from different building blocks of magnetic TI and nonmagnetic TI, providing new insights into the surface-bulk correspondence of magnetic TIs and guidance to heterostructure engineering in the emerging intrinsic magnetic topological systems
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
