Facet dependent surface energy gap on magnetic topological insulators

Abstract

Magnetic topological insulators (MnBi${}_2$Te${}_4$)(Bi${}_2$Te${}_3$)${}_n$ ($n=0,1,2,3$) are promising to realize exotic topological states such as the quantum anomalous Hall effect (QAHE) and axion insulator (AI), where the Bi${}_2$Te${}_3$ layer introduces versatility to engineer electronic and magnetic properties. However, whether surface states on the Bi${}_2$Te${}_3$ terminated facet are gapless or gapped is debated, and its consequences in thin-film properties are rarely discussed. In this work, we find that the Bi${}_2$Te${}_3$ terminated facets are gapless for $n\ge 1$ compounds by calculations. Despite that the surface Bi${}_2$Te${}_3$ (one layer or more) and underlying MnBi${}_2$Te${}_4$ layers hybridize and give rise to a gap, such a hybridization gap overlaps with bulk valence bands, leading to a gapless surface after all. Such a metallic surface poses a fundamental challenge to realize QAHE or AI, which requires an insulating gap in thin films with at least one Bi${}_2$Te${}_3$ surface. In theory, the insulating phase can still be realized in a film if both surfaces are MnBi${}_2$Te${}_4$ layers. Otherwise, it requires that the film thickness is less than 10$\sim$20 nm to push down bulk valence bands via the size effect. Our work paves the way to understand surface states and design bulk-insulating quantum devices in magnetic topological materials.

arXiv comment10 pages for the main text (4 figures) and 8 pages for supplemental material

References in corpus (54)

• Topological Insulators
• Topological insulators and superconductors
• Electronic Structure of Pyrochlore Iridates: From Topological Dirac Metal to Mott Insulator
• Weyl and Dirac Semimetals in Three Dimensional Solids
• Wannier90: A Tool for Obtaining Maximally-Localised Wannier Functions
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Topological Field Theory of Time-Reversal Invariant Insulators
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Topological Materials: Weyl Semimetals
• Magnetic-field-induced quantized anomalous Hall effect in intrinsic magnetic topological insulator MnBi${}_2$Te${}_4$
• Prediction and observation of the first antiferromagnetic topological insulator
• Intrinsic magnetic topological insulators in van der Waals layered MnBi${}_2$Te${}_4$-family materials
• Topological axion states in magnetic insulator MnBi${}_2$Te${}_4$ with the quantized magnetoelectric effect
• Robust axion insulator and Chern insulator phases in a two-dimensional antiferromagnetic topological insulator
• Quantum Anomalous Hall Effect in Hg${}_{1-y}$Mn${}_y$Te Quantum Wells
• Experimental realization of an intrinsic magnetic topological insulator
• Unique thickness-dependent properties of the van der Waals interlayer antiferromagnet $\mathrm{MnB}{\mathrm{i}}_2\mathrm{T}{\mathrm{e}}_4$ films
• High-Chern-Number and High-Temperature Quantum Hall Effect without Landau Levels
• Realization of the Axion Insulator State in Quantum Anomalous Hall Sandwich Heterostructures
• Gapless surface Dirac cone in antiferromagnetic topological insulator MnBi${}_2$Te${}_4$
• Topological Electronic Structure and Its Temperature Evolution in Antiferromagnetic Topological Insulator MnBi2Te4
• Intrinsic magnetic topological insulator phases in the Sb doped MnBi2Te4 bulks and thin flakes
• Dirac surface states in intrinsic magnetic topological insulators EuSn2As2 and MnBi2nTe3n+1
• Spin scattering and noncollinear spin structure-induced intrinsic anomalous Hall effect in antiferromagnetic topological insulator $\mathrm{MnB}{\mathrm{i}}_2\mathrm{T}{\mathrm{e}}_4$
• A van der Waals antiferromagnetic topological insulator with weak interlayer magnetic coupling
• Natural van der Waals heterostructural single crystals with both magnetic and topological properties
• Highly-ordered wide bandgap materials for quantized anomalous Hall and magnetoelectric effects
• Variety of magnetic topological phases in the (MnBi${}_2$Te${}_4$)(Bi${}_2$Te${}_3$)${}_m$ family
• Gapless Dirac surface states in the antiferromagnetic topological insulator MnBi2Te4
• Realization of an intrinsic, ferromagnetic topological state in MnBi8Te13
• Surface states and Rashba-type spin polarization in antiferromagnetic MnBi${}_2$Te${}_4$
• Observation of high-temperature quantum anomalous Hall regime in intrinsic MnBi${}_2$Te${}_4$/Bi${}_2$Te${}_3$ superlattice
• Topological electronic structure and intrinsic magnetization in MnBi${}_4$Te${}_7$: a Bi${}_2$Te${}_3$-derivative with a periodic Mn sublattice
• Robust A-type order and spin-flop transition on the surface of the antiferromagnetic topological insulator MnBi${}_2$Te${}_4$
• Coexistence of Surface Ferromagnetism and Gapless Topological State in MnBi${}_2$Te${}_4$
• Intrinsic axion insulating behavior in antiferromagnetic MnBi${}_6$Te${}_{10}$
• Magnetic topological insulator MnBi6Te10 with zero-field ferromagnetic state and gapped Dirac surface states
• Magnetic-field-induced robust zero Hall plateau state in MnBi${}_2$Te${}_4$ Chern insulator
• Intrinsic magnetic topological insulators
• Sample-dependent Dirac point gap in MnBi${}_2$Te${}_4$ and its response to the applied surface charge: a combined photoemission and ab initio study
• Distinct Topological Surface States on the Two Terminations of MnBi${}_4$Te${}_7$
• Universal gapless Dirac cone and tunable topological states in (MnBi${}_2$Te${}_4$)${}_m$(Bi${}_2$Te${}_3$)${}_n$ heterostructures
• Persistent gapless surface states in MnBi2Te4/Bi2Te3 superlattice antiferromagnetic topological insulator
• Magnetized Topological Insulator Multilayers
• Topological magnetic materials of the (MnSb${}_2$Te${}_4$)$\cdot$(Sb${}_2$Te${}_3$)${}_n$ van der Waals compounds family
• Orbital Complexity in Intrinsic Magnetic Topological Insulators MnBi${}_4$Te${}_7$ and MnBi${}_6$Te${}_{10}$
• Evidence for a magnetic-field induced ideal type-II Weyl state in antiferromagnetic topological insulator Mn(Bi1-xSbx)2Te4
• Routes to realize the axion-insulator phase in MnBi${}_2$Te${}_4$(Bi${}_2$Te${}_3$)${}_n$ family: a perspective
• Coexisting of Quantum Hall and Quantum Anomalous Hall phases in Disordered $\mathrm{MnB}{\mathrm{i}}_2\mathrm{T}{\mathrm{e}}_4$
• Hybridization-Induced Gapped and Gapless States on the Surfaces of Magnetic Topological Insulators
• Light-Tunable Surface State and Hybridization Gap in Magnetic Topological Insulator MnBi${}_8$Te${}_{13}$
• Experimental evidence on the dissipationless transport of chiral edge state of the high-field Chern insulator in MnBi2Te4 nanodevices
• Detection of magnetic gap in the topological surface states of MnBi2Te4
• Systemic Consequences of Disorder in Magnetically Self-Organized Topological MnBi${}_2$Te${}_4/$(Bi${}_2$Te${}_3$)${}_n$ Superlattices

Cited by in corpus (6)

• Unification of Nonlinear Anomalous Hall Effect and Nonreciprocal Magnetoresistance in Metals by the Quantum Geometry
• Distinct magnetic gaps between antiferromagnetic and ferromagnetic orders driven by surface defects in the topological magnet MnBi2Te4
• Magnetic Proximity Evoked Colossal Bulk Photovoltaics in Crystalline Symmetric Layers
• Fabrication-induced even-odd discrepancy of magnetotransport in few-layer MnBi${}_2$Te${}_4$
• Momentum-inversion symmetry breaking on the Fermi surface of magnetic topological insulators
• Resonantly enhanced photoemission from topological surface states in MnBi${}_6$Te${}_{10}$