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Ring states in topological materials

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arxiv 2406.03529 v1 pith:RGEBYS7L submitted 2024-06-05 cond-mat.mes-hall cond-mat.mtrl-sci

Ring states in topological materials

classification cond-mat.mes-hall cond-mat.mtrl-sci
keywords statesringbandeigenstatesenergyimpurityingaptopological
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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Ingap states are commonly observed in semiconductors and are often well characterized by a hydrogenic model within the effective mass approximation. However, when impurities are strong, they significantly perturb all momentum eigenstates, leading to deep-level bound states that reveal the global properties of the unperturbed band structure. In this work, we discover that the topology of band wavefunctions can impose zeros in the impurity-projected Green's function within topological gaps. These zeros can be interpreted as spectral attractors, defining the energy at which ingap states are pinned in the presence of infinitely strong local impurities. Their pinning energy is found by minimizing the level repulsion of band eigenstates onto the ingap state. We refer to these states as ring states, marked by a mixed band character and a node at the impurity site, guaranteeing their orthogonality to the bare impurity eigenstates and a weak energy dependence on the impurity strength. We show that the inability to construct symmetric and exponentially localized Wannier functions ensures topological protection of ring states. Linking ring states together, the edge or surface modes can be recovered for any topologically protected phase. Therefore, ring states can also be viewed as building blocks of boundary modes, offering a framework to understand bulk-boundary correspondence.

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Cited by 6 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Observation of ring states in a delicate topological insulator

    cond-mat.mes-hall 2026-04 unverdicted novelty 7.0

    Ring states around impurities act as a spectroscopic probe for delicate topological insulators in a phononic metamaterial and persist after multicellularity is removed by a weakly hybridizing orbital.

  2. Step-Edge Anomaly in Topological Metals

    cond-mat.mes-hall 2026-04 unverdicted novelty 7.0

    Step edges in 3D topological metals carry a robust non-integer conductance K e²/h determined by the bulk.

  3. Quantum Critical Dynamics Induced by Topological Zero Modes

    cond-mat.mes-hall 2025-02 unverdicted novelty 7.0

    Hybridized topological zero modes cause ac conductivity to scale as log ω at the critical delocalization point in the disordered SSH chain due to stretched-exponential wavefunction decay.

  4. Emergent superconductivity upon disordering a topological insulator

    cond-mat.supr-con 2026-07 conditional novelty 6.0

    Sign-problem-free QMC simulations show that strong impurities reduce the critical interaction for superconductivity in a BHZ-Hubbard model by nucleating Cooper pairs in impurity-induced subgap ring states.

  5. Topological random alloy

    cond-mat.mes-hall 2026-06 unverdicted novelty 6.0

    Minimal model of topological random binary alloy shows dopant-centric chiral current loops enabling topological phase transitions in trivial hosts and metallic phases with inter-domain edge modes in opposite-chirality cases.

  6. Poles-zeros duality in semi-holographic Mott insulators

    hep-th 2026-05 unverdicted novelty 5.0

    A semi-holographic model couples a fermion to a holographic composite sector, yielding poles-zeros duality in the Green's function that distinguishes metallic and Mott-insulating phases through choice of quantization.