Author(s):

New Evidence for Topological Insulator Property
Overclockers Club
They say one should not judge a book by its cover, but sometimes the cover is the most interesting part. Topological insulators (TIs) are a curious class of materials that conduct electricity on their surfaces, but not through their bulk. Researchers

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Author(s): Jonas Anversa, Paulo Piquini, Adalberto Fazzio, and Tome M. Schmidt

The observation of the quantum spin Hall effect without the need of an external magnetic field in HgTe/CdTe heterostructures triggered the study of materials exhibiting persistent spin-polarized electronic currents at their interfaces. These Dirac-like spin states are predicted to be topologically p…

[Phys. Rev. B 90, 195311] Published Fri Nov 21, 2014

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Author(s): Stefanos Kourtis and Maria Daghofer

We present a class of states with both topological and conventional Landau order that arise out of strongly interacting spinless fermions in fractionally filled and topologically nontrivial bands with Chern number C=±1. These quantum states show the features of fractional Chern insulators, such as f…

[Phys. Rev. Lett. 113, 216404] Published Fri Nov 21, 2014

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Author(s): B. J. Lawson, G. Li, F. Yu, T. Asaba, C. Tinsman, T. Gao, W. Wang, Y. S. Hor, and Lu Li

CuxBi2Se3 has drawn much attention as the leading candidate to be the first topological superconductor and the realization of coveted Majorana particles in a condensed matter system. However, there has been increasing controversy about the nature of its superconducting phase. This study sheds light …

[Phys. Rev. B 90, 195141] Published Fri Nov 21, 2014

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Author(s):Xiaofeng Qian

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New 3D topological insulator is the nearest to perfection yet
physicsworld.com
Researchers in the US say that they have made the best 3D topological insulator to date. The material is called bismuth antimony tellurium selenide (BiSbTeSe2) and could be of fundamental importance for testing a number of condensed-matter and …

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Author(s): Udit Khanna, Arijit Kundu, Saurabh Pradhan, and Sumathi Rao

We study superconducting proximity effects in Weyl semimetals (WSM) with broken time-reversal symmetry by tunnel-coupling one of its surfaces to an s-wave superconductor using the Green’s function approach. We find that the band structure develops coherence peaks, but despite the presence of metalli…

[Phys. Rev. B 90, 195430] Published Thu Nov 20, 2014

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Author(s):Miao Zhou

Formation of topological quantum phase on conventional semiconductor surface
is of both scientific and technological interest. Here, we demonstrate
epitaxial growth of 2D topological insulator, i.e. quantum spin Hall (QSH)
state, on Si(111) surface with a large energy gap, based on first-principles
calculations. We show that Si(111) surface functionalized with 1/3 monolayer of
halogen atoms [Si(111)-sqrt(3) x sqrt(3)-X (X=Cl, Br, I)] exhibiting a trigonal
superstructure, provides an ideal template for epitaxial growth of heavy
metals, such as Bi, which self-assemble into a hexagonal lattice with high
kinetic and thermodynamic stability. Most remarkably, the Bi overlayer is
“atomically” bonded to but “electronically” decoupled from the underlying Si
substrate, exhibiting isolated QSH state with an energy gap as large as 0.8 eV.
This surprising phenomenon is originated from an intriguing substrate orbital
filtering effect, which critically select the orbital composition around the
Fermi level leading to different topological phases. Particularly, the
substrate-orbital-filtering effect converts the otherwise topologically trivial
freestanding Bi lattice into a nontrivial phase; while the reverse is true for
Au lattice. The underlying physical mechanism is generally applicable, opening
a new and exciting avenue for exploration of large-gap topological
surface/interface states.

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Author(s): M. Benito, A. Gómez-León, V. M. Bastidas, T. Brandes, and G. Platero

Floquet Majorana fermions appear as steady states at the boundary of time-periodic topological phases of matter. In this work, we theoretically study the main features of these exotic topological phases in the periodically driven one-dimensional Kitaev model. By controlling the ac fields, we can pre…

[Phys. Rev. B 90, 205127] Published Wed Nov 19, 2014

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Author(s): A. Quelle and C. Morais Smith

In this paper, we investigate the occurrence of quantum phase transitions in topological systems out of equilibrium. More specifically, we consider graphene with a sizable spin-orbit coupling, irradiated by circularly polarized light. In the absence of light, the spin-orbit coupling drives a quantum…

[Phys. Rev. B 90, 195137] Published Wed Nov 19, 2014

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Author(s): A. Quelle and C. Morais Smith

In this paper, we investigate the occurrence of quantum phase transitions in topological systems out of equilibrium. More specifically, we consider graphene with a sizable spin-orbit coupling, irradiated by circularly polarized light. In the absence of light, the spin-orbit coupling drives a quantum…

[Phys. Rev. B 90, 195137] Published Wed Nov 19, 2014

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Author(s): A. Quelle and C. Morais Smith

In this paper, we investigate the occurrence of quantum phase transitions in topological systems out of equilibrium. More specifically, we consider graphene with a sizable spin-orbit coupling, irradiated by circularly polarized light. In the absence of light, the spin-orbit coupling drives a quantum…

[Phys. Rev. B 90, 195137] Published Wed Nov 19, 2014

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Author(s): A. Quelle and C. Morais Smith

In this paper, we investigate the occurrence of quantum phase transitions in topological systems out of equilibrium. More specifically, we consider graphene with a sizable spin-orbit coupling, irradiated by circularly polarized light. In the absence of light, the spin-orbit coupling drives a quantum…

[Phys. Rev. B 90, 195137] Published Wed Nov 19, 2014

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Author(s): A. Quelle and C. Morais Smith

In this paper, we investigate the occurrence of quantum phase transitions in topological systems out of equilibrium. More specifically, we consider graphene with a sizable spin-orbit coupling, irradiated by circularly polarized light. In the absence of light, the spin-orbit coupling drives a quantum…

[Phys. Rev. B 90, 195137] Published Wed Nov 19, 2014

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Author(s): A. Quelle and C. Morais Smith

In this paper, we investigate the occurrence of quantum phase transitions in topological systems out of equilibrium. More specifically, we consider graphene with a sizable spin-orbit coupling, irradiated by circularly polarized light. In the absence of light, the spin-orbit coupling drives a quantum…

[Phys. Rev. B 90, 195137] Published Wed Nov 19, 2014

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Author(s):Miao Zhou

For potential applications in spintronics and quantum computing, it is desirable to place a quantum spin Hall insulator [i.e., a 2D topological insulator (TI)] on a substrate while maintaining a large energy gap. Here, we demonstrate a unique approach to create the large-gap 2D TI state on a semiconductor surface, based on first-principles calculations and effective Hamiltonian analysis. We show that when heavy elements with strong spin orbit coupling (SOC) such as Bi and Pb atoms are deposited on a patterned H-Si(111) surface into a hexagonal lattice, they exhibit a 2D TI state with a large energy gap of ≥0.5 eV. The TI state arises from an intriguing substrate orbital filtering effect that selects a suitable orbital composition around the Fermi level, so that the system can be matched onto a four-band effective model Hamiltonian. Furthermore, it is found that within this model, the SOC gap does not increase monotonically with the increasing strength of SOC. These interesting results may shed new light in future design and fabrication of large-gap topological quantum states.

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IEEE Spectrum
Topological Insulators Move Closer to Practical Applications
IEEE Spectrum
Now researchers at Purdue University claim they have found evidence that is the “smoking gun” proving that topological insulators are indeed a path towards realizing practical quantum computers as well as “spintronic” devices that are far more powerful

and more »

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Author(s):


IEEE Spectrum
Topological Insulators Move Closer to Practical Applications
IEEE Spectrum
Now researchers at Purdue University claim they have found evidence that is the “smoking gun” proving that topological insulators are indeed a path towards realizing practical quantum computers as well as “spintronic” devices that are far more powerful

and more »

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Author(s):Tasinkevych, M., Campbell, M. G., Smalyukh, I. I.

Topologically nontrivial field excitations, including solitonic, linked, and knotted structures, play important roles in physical systems ranging from classical fluids and liquid crystals, to electromagnetism, classic, and quantum field theories. These excitations can appear spontaneously during symmetry-breaking phase transitions. For example, in cosmological theories, cosmic strings may have formed knotted…

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Author(s): Michael Hermele

We construct a family of exactly solvable spin models that illustrate a mechanism for fractionalization in topologically ordered phases, dubbed the string flux mechanism. The essential idea is that an anyon of a topological phase can be endowed with fractional quantum numbers when the string attache…

[Phys. Rev. B 90, 184418] Published Tue Nov 18, 2014

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