Non-magnetic defects in the bulk of two-dimensional topological insulators

Sukhanov²

2015

Phys. Rev. B

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We study in-gap electronic states induced by a nonmagnetic defect with short-range potential in two-dimensional topological insulators and trace their evolution as the distance between the defect and the boundary changes. The defect located far from the boundary is found to produce two bound states independently of the sign of its potential. The states are classified as electronlike and holelike. Each of these states can have two types of the spatial distribution of the electron density. The first-type states have a maximum of the density in the center and the second-type ones have a minimum. When the defect is coupled with the boundary, the bound states are transformed correspondingly into resonances of two types and take up the form of the edge states flowing around the defect. Under certain conditions, two resonances interfere giving rise to the formation of a bound state embedded into the continuum spectrum of the edge states flowing around the defect. We calculate the spatial distribution of the electron density in the edge states flowing around the defect and estimate the charge accumulated near the defect. The current density field of the edge states flowing around the defect contains two components one of which flows around the defect and the other circulates around it.

Section: Bound States In the Bulksupporting

confidence: 86%

“…This simplification allows us to calculate analytically the integrals over p in Eqs. (11) and (24). The subsequent integration over k is done numerically.…”

Section: Defect-induced States Near the Boundarymentioning

confidence: 99%

“…When the defect is located in the bulk, a circular electron current is present in each bound state with a given spin 24 . Its direction is locked to the spin as in the edge states.…”

Section: Electronic Structure Of States Flowing Around the Defectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Electronic states induced by nonmagnetic defects in two-dimensional topological insulators

Sukhanov²

2015

Phys. Rev. B

Self Cite

“…In the edge states the electrons move along the boundary and their spin is locked to the momentum because of strong spin-orbit interaction. In recent works [15,16] we have studied the electronic states induced by nonmagnetic defects and found that a defect with a short-range potential creates two bound states in contrast to topologically trivial insulators where only one bound state exists at such a defect. These states differ in both the pseudospin structure and the spatial distribution of the particle density.…”

Section: Introductionmentioning

confidence: 99%

Helical bound states in the continuum of the edge states in two dimensional topological insulators

Sukhanov

2015

Physics Letters A

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We study bound states embedded into the continuum of edge states in two-dimensional topological insulators. These states emerge in the presence of a short-range potential of a structural defect coupled to the boundary. In this case the edge states flow around the defect and have two resonances in the local density of states. The bound state in continuum (BIC) arises due to an interference of the resonances when they are close to the degeneracy. We find the condition under which the BIC appears, study the spacial distribution of the electron density, and show that the BIC has a helical structure with an electron current circulating around the defect.

Optical transitions in two-dimensional topological insulators with point defects

Physica B: Condensed Matter

Sukhanov

2016

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Nontrivial properties of electronic states in topological insulators are inherent not only to the surface and boundary states, but to bound states localized at structure defects as well. We clarify how the unusual properties of the defect-induced bound states are manifested in optical absorption spectra in two-dimensional topological insulators. The calculations are carried out for defects with short-range potential. We find that the defects give rise to the appearance of specific features in the absorption spectrum, which are an inherent property of topological insulators. They have the form of two or three absorption peaks that are due to intracenter transitions between electron-like and hole-like bound states.