Fate of surface gaps in magnetic topological insulators

Abstract

In magnetic topological insulators, the surface states can exhibit a gap due to the breaking of time-reversal symmetry. Various experiments, while suggesting the existence of the surface gap, have raised questions about its underlying mechanism in the presence of different magnetic orderings. Here, we demonstrate that magnon-mediated electron-electron interactions, whose effects are not limited to the surfaces perpendicular to the magnetic ordering, can significantly influence surface states and their effective gaps. On the surfaces perpendicular to the spin quantization axis, many-body interactions can enhance the band gap to a degree that surpasses the non-interacting scenario. Then, on surfaces parallel to the magnetic ordering, we find that strong magnon-induced fermionic interactions can lead to features resembling a massless-like gap. These remarkable results largely stem from the fact that magnon-mediated interactions exhibit considerable long-range behavior compared to direct Coulomb interactions among electrons, thereby dominating the many-body properties at the surface of magnetic topological insulators.

10+11 pages, 3+4 figures

References in corpus (22)

• Non-Abelian Anyons and Topological Quantum Computation
• Antiferromagnetic topological insulators
• Interactions and phase transitions on graphene's honeycomb lattice
• Progress and prospects in magnetic topological materials
• Axion Electrodynamics in Topological Materials
• Four-loop critical exponents for the Gross-Neveu-Yukawa models
• Cold atom simulation of interacting relativistic quantum field theories
• Mn-rich MnSb2Te4: A topological insulator with magnetic gap closing at high Curie temperatures of 45-50 K
• Half-Magnetic Topological Insulator
• Intrinsic magnetic topological insulators
• Routes to realize the axion-insulator phase in MnBi${}_2$Te${}_4$(Bi${}_2$Te${}_3$)${}_n$ family: a perspective
• Distinct magnetic gaps between antiferromagnetic and ferromagnetic orders driven by surface defects in the topological magnet MnBi2Te4
• Visualizing the interplay of Dirac mass gap and magnetism at nanoscale in intrinsic magnetic topological insulators
• Magnon-mediated superconductivity on the surface of a topological insulator
• Intrinsic Magnetic Topological Materials
• Spectroscopic Signatures of Massless Gap Opening in Graphene
• Strongly anisotropic spin dynamics in magnetic topological insulators
• Electron-magnon coupling and quasiparticle lifetimes on the surface of a topological insulator
• Strongly Gapped Topological Surface States on Protected Surfaces of Antiferromagnetic MnBi${}_4$Te${}_7$ and MnBi${}_6$Te${}_{10}$
• Magnetic warping in topological insulators
• Massless Dirac cones in graphene: experiments and theory
• Finite temperature fluctuation-induced order and responses in magnetic topological insulators