scholarly journals Spontaneous ferromagnetism and finite surface energy gap in the topological insulator Bi2Se3 from surface BiSe antisite defects

2020 ◽  
Vol 102 (14) ◽  
Author(s):  
Suhas Nahas ◽  
Biplab Sanyal ◽  
Annica M. Black-Schaffer
Keyword(s):  
Surface Energy ◽  
Topological Insulator ◽  
Energy Gap ◽  
Antisite Defects

Transport Properties of Topological Insulator Bi0.83Sb0.17 Nanowires

2015 ◽  
Vol 1785 ◽  
pp. 1-6
Author(s):  
L.A. Konopko ◽  
A.A. Nikolaeva ◽  
T.E. Huber ◽  
J.P. Ansermet
Keyword(s):  
Magnetic Field ◽  
Single Crystal ◽  
Transport Properties ◽  
Topological Insulator ◽  
Energy Gap ◽  
Oscillation Amplitude ◽  
Glass Capillary ◽  
Wire Axis ◽  
Temperature Dependences ◽  
The Wire

ABSTRACTWe have investigated the transport properties of topological insulator based on single-crystal Bi0.83Sb0.17 nanowires. The single-crystal nanowire samples in the diameter range 200 nm – 1.1 μm were prepared by the high frequency liquid phase casting in a glass capillary using an improved Ulitovsky technique; they were cylindrical single-crystals with (1011) orientation along the wire axis. In this orientation, the wire axis makes an angle of 19.5o with the bisector axis C1 in the bisector-trigonal plane. Bi0.83Sb0.17 is a narrow gap semiconductor with energy gap at L point of Brillouin zone ΔE= 21 meV. In accordance with the measurements of the temperature dependence of the resistivity of the samples resistance increases with decreasing temperature, but at low temperatures decrease in the resistance is observed. This effect, decrease in the resistance, is a clear manifestation of the interesting properties of topological insulators - the presence on its surface of a highly conducting zone. The Arrhenius plot of resistance R in samples with diameter d=1.1 µm and d=200 nm indicates a thermal activation behavior with an activation gap ΔE= 21 and 35 meV, respectively, which proves the presence of the quantum size effect in these samples. We found that in the range of diameter 1100 nm - 200 nm when the diameter decreases the energy gap is growing as 1/d. We have investigated magnetoresistance of Bi0.83Sb0.17 nanowires at various magnetic field orientations. From the temperature dependences of Shubnikov de Haas oscillation amplitude for different orientation of magnetic field we have calculated the cyclotron mass mc and Dingle temperature TD for longitudinal and transverse (B||C3 and B||C2) directions of magnetic fields, which equal 1.96*10-2m0, 9.8 K, 8.5*10-3m0 , 9.4 K and 1.5*10-1m0 , 2.8 K respectively. The observed effects are discussed.

Topological Properties in Strained Monolayer Antimony Iodide

2021 ◽  
Vol 38 (11) ◽  
pp. 117301
Author(s):  
Danwen Yuan ◽  
Yuefang Hu ◽  
Yanmin Yang ◽  
Wei Zhang
Keyword(s):  
Topological Insulator ◽  
Topological Insulators ◽  
Energy Gap ◽  
Square Lattice ◽  
Honeycomb Lattice ◽  
Type I ◽  
Topological Properties ◽  
Dirac Semimetal ◽  
Low Dissipation ◽  
Binary Compounds

Two-dimensional (2D) topological insulators present a special phase of matter manifesting unique electronic properties. Till now, many monolayer binary compounds of Sb element, mainly with a honeycomb lattice, have been reported as 2D topological insulators. However, research of the topological insulating properties of the monolayer Sb compounds with square lattice is still lacking. Here, by means of the first-principles calculations, a monolayer SbI with square lattice is proposed to exhibit the tunable topological properties by applying strain. At different levels of the strain, the monolayer SbI shows two different structural phases: buckled square structure and buckled rectangular structure, exhibiting attracting topological properties. We find that in the buckled rectangular phase, when the strain is greater than 3.78%, the system experiences a topological phase transition from a nontrivial topological insulator to a trivial insulator, and the structure at the transition point actually is a Dirac semimetal possessing two type-I Dirac points. In addition, the system can achieve the maximum global energy gap of 72.5 meV in the topological insulator phase, implying its promising application at room temperature. This study extends the scope of 2D topological physics and provides a platform for exploring the low-dissipation quantum electronics devices.

scholarly journals Resolving the topological classification of bismuth with topological defects

2019 ◽  
Vol 5 (11) ◽  
pp. eaax6996 ◽  
Author(s):  
Abhay Kumar Nayak ◽  
Jonathan Reiner ◽  
Raquel Queiroz ◽  
Huixia Fu ◽  
Chandra Shekhar ◽  
...  
Keyword(s):  
Screw Dislocation ◽  
Topological Insulator ◽  
Energy Gap ◽  
Topological Defects ◽  
Higher Order ◽  
Topological Classification ◽  
Wide Energy Range ◽  
The Status ◽  
The One

The growing diversity of topological classes leads to ambiguity between classes that share similar boundary phenomenology. This is the status of bulk bismuth. Recent studies have classified it as either a strong or a higher-order topological insulator, both of which host helical modes on their boundaries. We resolve the topological classification of bismuth by spectroscopically mapping the response of its boundary modes to a screw-dislocation. We find that the one-dimensional mode, on step-edges, extends over a wide energy range and does not open a gap near the screw-dislocations. This signifies that this mode binds to the screw-dislocation, as expected for a material with nonzero weak indices. We argue that the small energy gap, at the time reversal invariant momentum L, positions bismuth within the critical region of a topological phase transition between a higher-order topological insulator and a strong topological insulator with nonzero weak indices.

scholarly journals Квантовый размерный эффект и осцилляции Шубникова–де Гааза в поперечном магнитном поле в полупроводниковых нитях Bi0,92Sb0,08

2021 ◽  
Vol 57 (6) ◽  
pp. 79-86
Author(s):  
A.A. Nicolaeva ◽  
◽  
L.A. Conopco ◽  
I.A. Popov ◽  
G.I. Para ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Size Effect ◽  
Topological Insulator ◽  
Energy Gap ◽  
Surface States ◽  
Quantum Size Effect ◽  
Linear Dispersion ◽  
Quantum Size ◽  
Sdh Oscillations ◽  
The Wire

The transport properties, magnetoresistance, and Shubnikov–de Haas (SdH) oscillations of glass-coated Bi0.92Sb0.08 single-crystal wires with diameters of 180 nm to 2.2 mm and the (1011) orientation along the wire axis, which are prepared by liquid phase casting, have been studied. For the first time, it has been found that the energy gap DE increases by a factor of 4 with a decrease in the wire diameter d owing to the manifestation of the quantum size effect. This significant increase in the energy gap can occur under conditions of an energy–momentum linear dispersion relation, which is characteristic of both the gapless state and the surface states of a topological insulator. It has been shown that, in a strong magnetic field at low temperatures, a semiconductor–semimetal transition occurs; it is evident in the temperature dependences of resistance in a magnetic field. An analysis of the SdH oscillations, namely, the phase shift of the Landau levels and the features of the angular dependences of the oscillation periods, suggests that the combination of the manifestation of the topological insulator properties and the quantum size effect leads to the occurrence of new effects in low-dimensional structures, which requires new scientific approaches and applications in microelectronics

scholarly journals Direct detection of axion-like particles in Bismuth-based topological insulators

2018 ◽  
Vol 33 (23) ◽  
pp. 1850135 ◽  
Author(s):  
Tairan Liang ◽  
Bin Zhu ◽  
Ran Ding ◽  
Tianjun Li
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Topological Insulator ◽  
Topological Insulators ◽  
Energy Gap ◽  
Direct Detection ◽  
Electronic System ◽  
Electronic Systems ◽  
Small Energy ◽  
Nucleus Target

In recent years, a new field emerged in dark matter community and immediately attracted a multitude of theorists and experimentalists, that of light dark matter direct detection in electronic systems. The phenomenon is similar to nuclear recoil in elastic scattering between dark matter and nucleus but with different kinematics. Due to the small energy gap, the electronic system can probe sub-GeV dark matter rather than nucleus target. In particular, the absorption into materials can even detect ultralight dark matter within mass around meV. In terms of the equivalence between optical conductivity and absorption cross-section, axion detection can be computed in Bismuth-based topological insulators. It is found that topological insulator has strong sensitivity on axion and provides a complementary direct detection to superconductor and semiconductors. The novelty of topological insulator is that the thin film could even obtain the same sensitivity as a superconductor.

scholarly journals Observation of phononic helical edge states in a mechanical topological insulator

Science ◽  
2015 ◽  
Vol 349 (6243) ◽  
pp. 47-50 ◽  
Author(s):  
Roman Süsstrunk ◽  
Sebastian D. Huber
Keyword(s):  
Topological Insulator ◽  
Energy Gap ◽  
Equations Of Motion ◽  
Quantum Spin ◽  
Edge States ◽  
Acoustic Metamaterials ◽  
Wave Guides ◽  
Mechanical Oscillators ◽  
The Stability ◽  
Open Question

A topological insulator, as originally proposed for electrons governed by quantum mechanics, is characterized by a dichotomy between the interior and the edge of a finite system: The bulk has an energy gap, and the edges sustain excitations traversing this gap. However, it has remained an open question whether the same physics can be observed for systems obeying Newton’s equations of motion. We conducted experiments to characterize the collective behavior of mechanical oscillators exhibiting the phenomenology of the quantum spin Hall effect. The phononic edge modes are shown to be helical, and we demonstrate their topological protection via the stability of the edge states against imperfections. Our results may enable the design of topological acoustic metamaterials that can capitalize on the stability of the surface phonons as reliable wave guides.

scholarly journals A large-energy-gap oxide topological insulator based on the superconductor BaBiO3

2013 ◽  
Vol 9 (11) ◽  
pp. 709-711 ◽  
Author(s):  
Binghai Yan ◽  
Martin Jansen ◽  
Claudia Felser
Keyword(s):  
Topological Insulator ◽  
Energy Gap ◽  
Large Energy

Energy-Gap Opening Near the Dirac Point after the Deposition of Cobalt on the (0001) Surface of the Topological Insulator BiSbTeSe2

2020 ◽  
Vol 54 (9) ◽  
pp. 1051-1055
Author(s):  
A. K. Kaveev ◽  
A. G. Banshchikov ◽  
A. N. Terpitskiy ◽  
V. A. Golyashov ◽  
O. E. Tereshchenko ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Dirac Point ◽  
Energy Gap ◽  
Gap Opening
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