Complex band structure of topologically protected edge states

Dang, Xiaoqian; Burton, John; Kalitsov, Alan; Velev, Julian P.; Tsymbal, Evgeny Y.

doi:10.1103/physrevb.90.155307

Cited by 30 publications

(29 citation statements)

References 28 publications

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“…It is a tool successfully used for the analysis of the decay lengths of localized states in bulk systems [54][55][56], linear periodic molecules [57], as well as in graphene [58]; recently it has also been applied to topological insulators [59,60]. Here we additionally employ it to explain the oscillations of the corrugation-confined states.…”

Section: B Model and Methodsmentioning

confidence: 99%

Topologically confined states at corrugations of gated bilayer graphene

Pelc¹,

Jaskólski²,

Ayuela³

et al. 2015

Phys. Rev. B

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We investigate the electronic and transport properties of gated bilayer graphene with one corrugated layer, which results in a stacking AB/BA boundary. When a gate voltage is applied to one layer, topologically protected gap states appear at the corrugation, which reveal as robust transport channels along the stacking boundary. With increasing size of the corrugation, more localized, quantum-well-like states emerge. These finite-size states are also conductive along the fold, but in contrast to the stacking boundary states, which are gapless, they present a gap. We have also studied periodic corrugations in bilayer graphene; our findings show that such corrugations between AB-and BA-stacked regions behave as conducting channels that can be easily identified by their shape.

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Section: B Model and Methodsmentioning

confidence: 99%

Topologically confined states at corrugations of gated bilayer graphene

Pelc¹,

Jaskólski²,

Ayuela³

et al. 2015

Phys. Rev. B

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“…This process becomes simple if there is no hybridization in the system and these bands with d-orbital character are well separated from other bands like the p-bands. As Dang et al 72 pointed out, a mixing of these d orbital bands with p orbital bands can create several complications.…”

Section: F Application To Real Materials: Srvo3mentioning

confidence: 99%

A multi-orbital iterated perturbation theory for model Hamiltonians and real material-specific calculations of correlated systems

et al. 2016

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Perturbative schemes utilizing a spectral moment expansion are well known and extensively used for investigating the physics of model Hamiltonians and real material systems (in combination with density functional theory). However, such methods are not always reliable in various parameter regimes such as in the proximity of phase transitions or for strong couplings. Nevertheless, the advantages they offer, in terms of being computationally inexpensive, with real frequency output at zero and finite temperatures, compensate for their deficiencies and offer a quick, qualitative analysis of the system behavior. In this work, we have developed such a method, that can be classified as a multi-orbital iterative perturbation theory (MO-IPT) to study N-fold degenerate and non degenerate Anderson impurity models. As applications of the solver, we have combined the method with dynamical mean field theory to explore lattice models like the single orbital Hubbard model, covalent band insulator and the multi-orbital Hubbard model for density-density type interactions in different parameter regimes. The Hund's coupling effects in case of multiple orbitals is also studied. The limitations and quality of results are gauged through extensive comparison with data from the numerically exact continuous time quantum Monte Carlo method (CTQMC). In the case of the single orbital Hubbard model, covalent band insulators and non degenerate multi-orbital Hubbard models, we obtained an excellent agreement between the Matsubara self-energies of MO-IPT and CTQMC. But for the degenerate multi-orbital Hubbard model, we observe that the agreement with CTQMC results gets better as we move away from particle-hole symmetry. We have integrated MO-IPT with density functional theory based electronic structure methods to study real material systems. As a test case, we have studied the classic, strongly correlated electronic material, SrVO3. A comparison of density of states and photo emission spectrum (PES) with results obtained from different impurity solvers and experiments yields good agreement.

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“…For our calculations we choose A to be the unit of energy and consider B = 1.0A,M = −1.5A that ensures the existence of topologically protected edge states for nonmagnetic TI. To map this bulk Hamiltonian (1) on a finite scattering region, we first extract the tight-binding parameters [83,86] by expressing…”

Section: Methodsmentioning

confidence: 99%

Spin-orbit torque in two-dimensional antiferromagnetic topological insulators

Ghosh

Manchon

2017

Phys. Rev. B

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We investigate spin transport in two-dimensional ferromagnetic (FTI) and antiferromagnetic (AFTI) topological insulators. In the presence of an in-plane magnetization AFTI supports zero energy modes, which enables topologically protected edge conduction at low energy. We address the nature of current-driven spin torque in these structures and study the impact of spin-independent disorder. Interestingly, upon strong disorder the spin torque develops an antidamping component (i.e., even upon magnetization reversal) along the edges, which could enable current-driven manipulation of the antiferromagnetic order parameter. This antidamping torque decreases when increasing the system size and when the system enters the trivial insulator regime.

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Complex band structure of topologically protected edge states

Cited by 30 publications

References 28 publications

Topologically confined states at corrugations of gated bilayer graphene

Topologically confined states at corrugations of gated bilayer graphene

A multi-orbital iterated perturbation theory for model Hamiltonians and real material-specific calculations of correlated systems

Spin-orbit torque in two-dimensional antiferromagnetic topological insulators

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