Chirality reversal at finite magnetic impurity strength and local signatures of a topological phase transition

Abstract

We study the honeycomb lattice with a single magnetic impurity modeled by adding imaginary next-nearest-neighbor hopping ih on a single hexagon. This Haldane defect gives a topological mass term to the gapless Dirac cones and generates chirality. For a small density of defects Neehus et al [arXiv:2405.19289] found that the system's chirality reverses at a critical hc ~ 0.95 associated with an unexpected tri-critical point of Dirac fermions at zero defect density. We investigate this zero-density limit by analyzing a single defect and computing two experimentally relevant measures of chirality: (1) orbital magnetization via local Chern marker, a bulk probe of all occupied states; and (2) electronic currents of low-energy states. Both probes show a chirality reversal at a critical hc ~ 0.9--1. Motivated by this consistency we propose a defect-scale toy model whose low energy states reverse their chirality at hc' ~ 0.87. Remarkably, the same pair of zero energy bound states also generate the critical point hc in the full impurity projected T-matrix. Our results show how the chirality reversal produced by an impurity can be observed either in local probes or in the global topology and suggest a possible role of the microscopic defect structure at the critical point.

arXiv comment10 pages, 5 figures; appendix 4 pages, 5 figures. v2: Published version

References in corpus (38)

• Anyons in an exactly solved model and beyond
• Topological insulators and superconductors: ten-fold way and dimensional hierarchy
• Periodic table for topological insulators and superconductors
• Magnetism in Graphene Induced by Single-Atom Defects
• Kwant: a software package for quantum transport
• The missing atom as a source of carbon magnetism
• Topological Anderson Insulator
• Theory of the topological Anderson insulator
• Observation of the topological Anderson insulator in disordered atomic wires
• Orbital magnetization in crystalline solids: Multi-band insulators, Chern insulators, and metals
• Mapping topological order in coordinate space
• Quantum imaging of current flow in graphene
• Control and Local Measurement of the Spin Chemical Potential in a Magnetic Insulator
• Impurity States in Graphene
• Impurity Bound States and Greens Function Zeroes as Local Signatures of Topology
• The two-dimensional random-bond Ising model, free fermions and the network model
• Disordered 2d quasiparticles in class D: Dirac fermions with random mass, and dirty superconductors
• Stabilizing topological phases in graphene via random adsorption
• Thermal metal in network models of a disordered two-dimensional superconductor
• Random-bond Ising model in two dimensions, the Nishimori line, and supersymmetry
• Criticality in the two-dimensional random-bond Ising model
• Orbital Magnetization as a Local Property
• Vanishing edge currents in non-$p$-wave topological chiral superconductors
• Effective mass and tricritical point for lattice fermions localized by a random mass
• Magnetic impurities in the honeycomb Kitaev model
• Featureless and non-fractionalized Mott insulators on the honeycomb lattice at 1/2 site filling
• Patched Green's function techniques for two dimensional systems: Electronic behaviour of bubbles and perforations in graphene
• Band dispersion of graphene with structural defects
• In-gap impurity states as the hallmark of the Quantum Spin Hall phase
• Local Chern Marker for Periodic Systems
• Griffiths phase in the thermal quantum Hall effect
• Local control of a single nitrogen-vacancy center by nanoscale engineered magnetic domain wall motions
• Impurity induced current in a Chern insulator
• Bound states and local topological phase diagram of classical impurity spins coupled to a Chern insulator
• Magnetic order through Kondo coupling to quantum spin liquids
• Disorder-induced currents as signatures of chiral superconductivity
• Genuine topological Anderson insulator from impurity induced chirality reversal
• Sharp spectroscopic fingerprints of disorder in an incompressible magnetic state