Structural Amorphization-Induced Topological Order

Wang, Citian; Cheng, Ting; Liu, Zhongfan; Liu, Feng; Huang, Huaqing

doi:10.1103/physrevlett.128.056401

Cited by 35 publications

(26 citation statements)

References 95 publications

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“…Thus, an amorphous system can be regarded as a clean system with structural disorder in some sense. Very recently, the structural disorder-induced first-order and second-order topological phase transitions have been proposed [93,104]. According to our calculations, it is found that density can drive higher-order topological phase transition in amorphous systems.…”

Section: Conclusion and Discussionsupporting

confidence: 50%

Density-driven higher-order topological phase transitions in amorphous solids

Tan¹,

Hua²,

Chen³

et al. 2022

Preprint

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The amorphous topological states, which are independent of the specific spatial distribution of the microscopic constructions, have gained much attention. Recently, higher-order topological insulators, which are a new class of topological phases of matter, have been proposed in amorphous systems. Here, we propose a densitydriven higher-order topological phase transition in two-dimensional amorphous system. We demonstrate that the amorphous system hosts a topological trivial phase at low density. With the increase in the density of lattice sites, the topological trivial phase converts to a higher-order topological phase characterized by quantized quadrupole moment and the existence of the topological corner states. Furthermore, we confirm that the densitydriven higher-order topological phase transition is size-dependent. In addition, our results should be general and equally applicable to three-dimensional amorphous systems. Our findings point has greatly enriched the study of higher-order topological states in amorphous systems.

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Section: Conclusion and Discussionsupporting

confidence: 50%

Density-driven higher-order topological phase transitions in amorphous solids

Tan¹,

Hua²,

Chen³

et al. 2022

Preprint

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show abstract

“…17−22 An example is that structural disorder by amorphization in stanane, a hydrogenated α-Sn(111) monolayer, can induce electronic order of topology in an otherwise topologically trivial crystal. 23 In parallel to the theoretical studies, we carried out highresolution surface-diffraction experiments using Spot Profile Analysis Low-Energy Electron Diffraction (SPA-LEED) to assess the structure and homogeneity of the intercalated Pb phases. These experiments provide a global characterization of the intercalated layer from quantitative analysis of all diffraction spots.…”

mentioning

confidence: 99%

“…In contrast to the former simplified picture, we find a family of more complex thermodynamically preferred Pb intercalated phases having a high degree of degeneracy. Clarifying the structure of the intercalated Pb monolayer is extremely important because different structures or phases for a 2D material can result in completely different electronic properties. − An example is that structural disorder by amorphization in stanane, a hydrogenated α-Sn(111) monolayer, can induce electronic order of topology in an otherwise topologically trivial crystal …”

mentioning

confidence: 99%

Degeneracy in Intercalated Pb Phases under Buffer-Layer Graphene on SiC(0001) and Diffuse Moiré Spots in Surface Diffraction

Han

Chen

Hall

et al. 2023

J. Phys. Chem. Lett.

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First-principles density functional theory (DFT) is used to analyze the stability of Pb intercalated phases under buffer layer graphene on SiC(0001) as a function of the supercell size, Pb coverage, and degree of Pb ordering. By comparing the chemical potentials of such two-dimensional Pb structures, we find that there is a family of structurally distinct thermodynamically preferred Pb subsurface configurations with minute stability differences. These differences are comparable to the thermal energies at about 450 °C, where the Pb intercalated phases are grown. High-resolution surface-diffraction experiments using Spot Profile Analysis Low-Energy Electron Diffraction (SPA-LEED) confirm this high degree of degeneracy of the Pb intercalated phases from broad, low-intensity moiré spots observed exclusively from intercalated Pb. The low intensity of the moiré spots implies the coexistence of structurally different subsurface Pb phases.

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“…Recently, the question of the existence of amorphous topological phases has received increasing interest, from experiments with mechanical systems (17) to theoretical investigations of random fermionic tight-binding lattices (18)(19)(20)(21)(22)(23) and quantum spin liquids (24,25). Topological edge states were then shown to be robust to structural disorder, provided that they lie in a mobility gap (26)(27)(28)(29), similarly to topological Anderson insulators (30).…”

Section: Introductionmentioning

confidence: 99%

Anomalous topological waves in strongly amorphous scattering networks

2023

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Topological insulators are crystalline materials that have revolutionized our ability to control wave transport. They provide us with unidirectional channels that are immune to obstacles, defects, or local disorder and can even survive some random deformations of their crystalline structures. However, they always break down when the level of disorder or amorphism gets too large, transitioning to a topologically trivial Anderson insulating phase. We demonstrate a two-dimensional amorphous topological regime that survives arbitrarily strong levels of amorphism. We implement it for electromagnetic waves in a nonreciprocal scattering network and experimentally demonstrate the existence of unidirectional edge transport in the strong amorphous limit. This edge transport is shown to be mediated by an anomalous edge state whose topological origin is evidenced by direct topological invariant measurements. Our findings extend the reach of topological physics to a class of systems in which strong amorphism can induce, enhance, and guarantee the topological edge transport instead of impeding it.

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Structural Amorphization-Induced Topological Order

Cited by 35 publications

References 95 publications

Density-driven higher-order topological phase transitions in amorphous solids

Density-driven higher-order topological phase transitions in amorphous solids

Degeneracy in Intercalated Pb Phases under Buffer-Layer Graphene on SiC(0001) and Diffuse Moiré Spots in Surface Diffraction

Anomalous topological waves in strongly amorphous scattering networks

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