Stacking Faults and Topological Properties in MnBi2Te4: Reconciling Gapped and Gapless States

Jeonghwan Ahn; Seoung Hun Kang; Mina Yoon; Panchapakesan Ganesh; Jaron T. Krogel

doi:10.1021/acs.jpclett.3c01939

Stacking Faults and Topological Properties in MnBi₂Te₄: Reconciling Gapped and Gapless States

Jeonghwan Ahn, Seoung Hun Kang, Mina Yoon, Panchapakesan Ganesh, Jaron T. Krogel

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

Despite theoretical predictions of a gapped surface state for the magnetic topological insulator MnBi₂Te₄ (MBT), there has been a series of experimental evidence pointing toward gapless states. Here, we theoretically explore how stacking faults could influence the topological characteristics of MBT. We envisage a scenario that a stacking fault exists at the surface of MBT, causing the uppermost layer to deviate from the ground state and its interlayer separation to be expanded. This stacking fault with modulated interlayer couplings hosts a nearly gapless state within the topmost layer due to charge redistribution as the outermost layer recedes. Furthermore, we find evidence of spin-momentum locking and preservation of weak band inversion in the gapless surface state, suggesting the nontrivial topological surface states in the presence of the stacking fault. Our findings provide a plausible elucidation to the long-standing conundrum of reconciling the observation of gapped and gapless states on MBT surfaces.

Original language	English
Pages (from-to)	9052-9059
Number of pages	8
Journal	Journal of Physical Chemistry Letters
Volume	14
Issue number	40
DOIs	https://doi.org/10.1021/acs.jpclett.3c01939
State	Published - Oct 12 2023

Funding

Work performed by J. A., P.G., and J.T.K. (DFT calculations, original idea) was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences, and Engineering Division, as part of the Computational Materials Sciences Program and Center for Predictive Simulation of Functional Materials. Work performed by S.-H.K. and M.Y. (topological index and spin texture calculations) was supported by the U.S. Department of Energy (DOE), Office of Science, National Quantum Information Science Research Centers, and Quantum Science Center. An award for computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. This research used resources of the Oak Ridge Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC05-00OR22725. This research also utilized resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 using NERSC award m2113-BES-ERCAP0024568.

Funders	Funder number
National Quantum Information Science Research Centers
Quantum Science Center
U.S. Department of Energy
Office of Science	DE-AC05-00OR22725, DE-AC02-05CH11231
Basic Energy Sciences
Division of Materials Sciences and Engineering

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abstract = "Despite theoretical predictions of a gapped surface state for the magnetic topological insulator MnBi2Te4 (MBT), there has been a series of experimental evidence pointing toward gapless states. Here, we theoretically explore how stacking faults could influence the topological characteristics of MBT. We envisage a scenario that a stacking fault exists at the surface of MBT, causing the uppermost layer to deviate from the ground state and its interlayer separation to be expanded. This stacking fault with modulated interlayer couplings hosts a nearly gapless state within the topmost layer due to charge redistribution as the outermost layer recedes. Furthermore, we find evidence of spin-momentum locking and preservation of weak band inversion in the gapless surface state, suggesting the nontrivial topological surface states in the presence of the stacking fault. Our findings provide a plausible elucidation to the long-standing conundrum of reconciling the observation of gapped and gapless states on MBT surfaces.",

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AU - Ganesh, Panchapakesan

AU - Krogel, Jaron T.

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AB - Despite theoretical predictions of a gapped surface state for the magnetic topological insulator MnBi2Te4 (MBT), there has been a series of experimental evidence pointing toward gapless states. Here, we theoretically explore how stacking faults could influence the topological characteristics of MBT. We envisage a scenario that a stacking fault exists at the surface of MBT, causing the uppermost layer to deviate from the ground state and its interlayer separation to be expanded. This stacking fault with modulated interlayer couplings hosts a nearly gapless state within the topmost layer due to charge redistribution as the outermost layer recedes. Furthermore, we find evidence of spin-momentum locking and preservation of weak band inversion in the gapless surface state, suggesting the nontrivial topological surface states in the presence of the stacking fault. Our findings provide a plausible elucidation to the long-standing conundrum of reconciling the observation of gapped and gapless states on MBT surfaces.

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Stacking Faults and Topological Properties in MnBi₂Te₄: Reconciling Gapped and Gapless States

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