scholarly journals Exceptional topological insulators

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
M. Michael Denner ◽  
Anastasiia Skurativska ◽  
Frank Schindler ◽  
Mark H. Fischer ◽  
Ronny Thomale ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Three Dimensional ◽  
Surface States ◽  
Exceptional Point ◽  
Weyl Semimetal ◽  
Complex Eigenvalues ◽  
Topological State ◽  
Single Sheet ◽  
Bulk Energy ◽  
State Of Matter

AbstractWe introduce the exceptional topological insulator (ETI), a non-Hermitian topological state of matter that features exotic non-Hermitian surface states which can only exist within the three-dimensional topological bulk embedding. We show how this phase can evolve from a Weyl semimetal or Hermitian three-dimensional topological insulator close to criticality when quasiparticles acquire a finite lifetime. The ETI does not require any symmetry to be stabilized. It is characterized by a bulk energy point gap, and exhibits robust surface states that cover the bulk gap as a single sheet of complex eigenvalues or with a single exceptional point. The ETI can be induced universally in gapless solid-state systems, thereby setting a paradigm for non-Hermitian topological matter.

Topological phases of a three-dimensional topological insulator with structure inversion asymmetry

2015 ◽  
Vol 29 (06) ◽  
pp. 1550034 ◽  
Author(s):  
Xiaoyong Guo ◽  
Zaijun Wang ◽  
Qiang Zheng ◽  
Jie Peng
Keyword(s):  
Phase Diagram ◽  
Topological Insulator ◽  
Tight Binding ◽  
Three Dimensional ◽  
Surface States ◽  
Topological Phases ◽  
Zeeman Field ◽  
Surface Modes ◽  
Inversion Asymmetry ◽  
Structure Inversion

We investigate the topological phases of a three-dimensional (3D) topological insulator (TI) without the top–bottom inversion symmetry. We calculate the momentum depended spin Chern number to extract the phase diagram. Various phases are found and we address the dependence of phase boundaries on the strength of inversion asymmetry. Opposite to the quasi-two-dimensional thin film TI, in our 3D system the TI state is stabilized by the structure inversion asymmetry (SIA). With a strong SIA the 3D TI phase can exist even under a large Zeeman field. In a tight-binding form, the surface modes are discussed to confirm with the phase diagram. Particularly we find that the SIA cannot destroy the surface states but open a gap on its spectrum.

Multiple Coexisting Dirac Surface States in Three-Dimensional Topological Insulator PbBi6Te10

ACS Nano ◽  
2016 ◽  
Vol 10 (3) ◽  
pp. 3518-3524 ◽  
Author(s):  
Marco Papagno ◽  
Sergey V. Eremeev ◽  
Jun Fujii ◽  
Ziya S. Aliev ◽  
Mahammad B. Babanly ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Three Dimensional ◽  
Surface States

scholarly journals Emergent Helical Edge States in a Hybridized Three-Dimensional Topological Insulator

2021 ◽  
Author(s):  
Su Kong Chong ◽  
Lizhe Liu ◽  
Kenji Watanabe ◽  
Takashi Taniguchi ◽  
Taylor Sparks ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Quantum Tunneling ◽  
Three Dimensional ◽  
Quantum Spin ◽  
Topological Phase ◽  
Edge States ◽  
Experimental Realization ◽  
Transition Mechanism ◽  
Topological Quantum ◽  
Topological State

Abstract As the thickness of a three-dimensional (3D) topological insulator (TI) becomes comparable to the penetration depth of surface states, quantum tunneling between surfaces turns their gapless Dirac electronic structure into a gapped spectrum. Whether the surface hybridization gap can host topological edge states is still an open question. Herein, we provide transport evidence of 2D topological states in the quantum tunneling regime of a bulk insulating 3D TI BiSbTeSe2. Different from its trivial insulating phase, this 2D topological state exhibits a finite longitudinal conductance at ~2e2/h when the Fermi level is aligned within the surface gap, indicating an emergent quantum spin Hall (QSH) state. The transition from the QSH to quantum Hall (QH) state in a transverse magnetic field further supports the existence of this distinguished 2D topological phase. In addition, we demonstrate a second route to realize the 2D topological state via surface gap-closing and topological phase transition mechanism mediated by a transverse electric field. The experimental realization of the 2D topological phase in a 3D TI enriches its phase diagram and marks an important step toward functional topological quantum devices.

Near-Field Tomography and Spectroscopy of Surface States on a Three-Dimensional Topological Insulator

2019 ◽  
Author(s):  
Fabian Sandner ◽  
Fabian Mooshammer ◽  
Markus A. Huber ◽  
Martin Zizlsperger ◽  
Helena Weigand ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Near Field ◽  
Three Dimensional ◽  
Surface States

Spin Ordering on the Surface of a Topological Insulator with Magnetic Ions

2012 ◽  
Vol 190 ◽  
pp. 494-497
Author(s):  
V.N. Men'shov ◽  
V.V. Tugushev ◽  
E.V. Chulkov
Keyword(s):  
Topological Insulator ◽  
Chemical Potential ◽  
Mean Field ◽  
Three Dimensional ◽  
Surface States ◽  
Dirac Fermions ◽  
Uniform Magnetization ◽  
Out Of Plane ◽  
Different Temperatures ◽  
Magnetic Ions

We study the effect of magnetic doping on appearance of ferromagnetic (FM) order on the surface of a three-dimensional topological insulator. Assuming the exchange coupling of the Dirac fermions with the dilute magnetic ions, we find that the system under consideration is unstable with respect to a spontaneous uniform magnetization along the out-of-plane direction. The appearance of the magnetization is accompanied by opening of a gap in the spectrum of surface states. In the framework of a mean-field approach, we analyze the possibility of the FM order on the magnetically doped surface of topological insulator at different temperatures and positions of the chemical potential.

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