scholarly journals Manipulation of Topological States and the Bulk Band Gap Using Natural Heterostructures of a Topological Insulator

2012 ◽  
Vol 109 (23) ◽  
Author(s):  
K. Nakayama ◽  
K. Eto ◽  
Y. Tanaka ◽  
T. Sato ◽  
S. Souma ◽  
...  
Keyword(s):  
Band Gap ◽  
Topological Insulator ◽  
Topological States ◽  
Bulk Band

scholarly journals Observation and control of the weak topological insulator state in ZrTe5

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Peng Zhang ◽  
Ryo Noguchi ◽  
Kenta Kuroda ◽  
Chun Lin ◽  
Kaishu Kawaguchi ◽  
...  
Keyword(s):  
Band Gap ◽  
Topological Insulator ◽  
Spin Current ◽  
Side Surface ◽  
Quantum Spin ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Dirac Semimetal ◽  
Topological States ◽  
The One ◽  
And Control

AbstractA quantum spin Hall (QSH) insulator hosts topological states at the one-dimensional (1D) edge, along which backscattering by nonmagnetic impurities is strictly prohibited. Its 3D analogue, a weak topological insulator (WTI), possesses similar quasi-1D topological states confined at side surfaces. The enhanced confinement could provide a route for dissipationless current and better advantages for applications relative to strong topological insulators (STIs). However, the topological side surface is usually not cleavable and is thus hard to observe. Here, we visualize the topological states of the WTI candidate ZrTe5 by spin and angle-resolved photoemission spectroscopy (ARPES): a quasi-1D band with spin-momentum locking was revealed on the side surface. We further demonstrate that the bulk band gap is controlled by external strain, realizing a more stable WTI state or an ideal Dirac semimetal (DS) state. The highly directional spin-current and the tunable band gap in ZrTe5 will provide an excellent platform for applications.

scholarly journals Graphene-Based Topological Insulator with an Intrinsic Bulk Band Gap above Room Temperature

Nano Letters ◽  
2013 ◽  
Vol 13 (12) ◽  
pp. 6251-6255 ◽  
Author(s):  
Liangzhi Kou ◽  
Binghai Yan ◽  
Feiming Hu ◽  
Shu-Chun Wu ◽  
Tim O. Wehling ◽  
...  
Keyword(s):  
Band Gap ◽  
Topological Insulator ◽  
Room Temperature ◽  
Bulk Band

scholarly journals Enhanced surface state protection and band gap in the topological insulator PbBi4Te4S3

2018 ◽  
Vol 2 (10) ◽  
Author(s):  
K. Sumida ◽  
T. Natsumeda ◽  
K. Miyamoto ◽  
I. V. Silkin ◽  
K. Kuroda ◽  
...  
Keyword(s):  
Band Gap ◽  
Topological Insulator ◽  
Surface State ◽  
Enhanced Surface ◽  
State Protection

scholarly journals Dimensional Crossover and Topological Nature of the Thin Films of a Three-Dimensional Topological Insulator by Band Gap Engineering

Nano Letters ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 4627-4633 ◽  
Author(s):  
Zhenyu Wang ◽  
Tong Zhou ◽  
Tian Jiang ◽  
Hongyi Sun ◽  
Yunyi Zang ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Topological Insulator ◽  
Three Dimensional ◽  
Dimensional Crossover ◽  
Band Gap Engineering

scholarly journals Surface electronic structure of the wide band gap topological insulator PbBi4Te4Se3

2019 ◽  
Vol 100 (19) ◽  
Author(s):  
I. A. Shvets ◽  
I. I. Klimovskikh ◽  
Z. S. Aliev ◽  
M. B. Babanly ◽  
F. J. Zúñiga ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Topological Insulator ◽  
Wide Band ◽  
Wide Band Gap ◽  
Surface Electronic Structure

Tuning Quantum Dot Luminescence Below the Bulk Band Gap Using Tensile Strain

ACS Nano ◽  
2013 ◽  
Vol 7 (6) ◽  
pp. 5017-5023 ◽  
Author(s):  
Paul J. Simmonds ◽  
Christopher D. Yerino ◽  
Meng Sun ◽  
Baolai Liang ◽  
Diana L. Huffaker ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Band Gap ◽  
Tensile Strain ◽  
Bulk Band

scholarly journals Symmetry-protected hierarchy of anomalous multipole topological band gaps in nonsymmorphic metacrystals

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiujuan Zhang ◽  
Zhi-Kang Lin ◽  
Hai-Xiao Wang ◽  
Zhan Xiong ◽  
Yuan Tian ◽  
...  
Keyword(s):  
Band Gap ◽  
Topological States Of Matter ◽  
Quantum Spin ◽  
Band Gaps ◽  
Quantum Spin Hall Effect ◽  
Classical Systems ◽  
Topological Materials ◽  
And Topology ◽  
Topological States ◽  
Symmetry Protected

AbstractSymmetry and topology are two fundamental aspects of many quantum states of matter. Recently new topological materials, higher-order topological insulators, were discovered, featuring bulk–edge–corner correspondence that goes beyond the conventional topological paradigms. Here we discover experimentally that the nonsymmorphic p4g acoustic metacrystals host a symmetry-protected hierarchy of topological multipoles: the lowest band gap has a quantized Wannier dipole and can mimic the quantum spin Hall effect, whereas the second band gap exhibits quadrupole topology with anomalous Wannier bands. Such a topological hierarchy allows us to observe experimentally distinct, multiplexed topological phenomena and to reveal a topological transition triggered by the geometry transition from the p4g group to the C4v group, which demonstrates elegantly the fundamental interplay between symmetry and topology. Our study demonstrates that classical systems with controllable geometry can serve as powerful simulators for the discovery of novel topological states of matter and their phase transitions.

OPTICAL ABSORPTION BEHAVIOR OF Co (II) ION DOPED PVA ASSISTED CdSe NANOPARTICLES

2013 ◽  
Vol 22 ◽  
pp. 346-350
Author(s):  
K. RAVINDRANADH ◽  
R. V. S. S. N. RAVIKUMAR ◽  
M. C. RAO
Keyword(s):  
Band Gap ◽  
Room Temperature ◽  
Urbach Energy ◽  
Wavelength Region ◽  
Wide Band ◽  
Cdse Nanoparticles ◽  
Poly Vinyl Alcohol ◽  
Wide Band Gap ◽  
Direct Band ◽  
Bulk Band

CdSe is an important II-VI, n-type direct band gap semiconductor with wide band gap (bulk band gap of 2.6 eV) and an attractive host for the development of doped nanoparticles. Poly vinyl alcohol (PVA) is used as a capping agent to stabilize the CdSe nanoparticles. The optical properties of Co (II) ion doped PVA capped CdSe nanoparticles grown at room temperature are studied in the wavelength region of 200-1400 nm. The spectrum of Co (II) ion doped PVA capped CdSe nanoparticles exhibit five bands at 1185, 620, 602, 548 and 465 nm (8437, 16125, 16607, 18243 and 21499 cm-1). The bands observed at 1185, 548 and 465 nm are correspond to the three spin allowed transitions 4T1g (F) → 4T2g (F), 4T1g (F) → 4A2g (F) and 4T1g (F) → 4T1g (P) respectively. The other bands observed at 602 nm and 620 nm are assigned to spin forbidden transitions 4T1g (F) → 2T2g (G), 4T1g (F) → 2T1g (G) . The small value of the Urbach energy indicates greater stability of the prepared sample.

OPTICAL SECOND HARMONIC SPECTROSCOPY OF THE ANATASE TiO2(101) FACE

2001 ◽  
Vol 15 (28n30) ◽  
pp. 3873-3876 ◽  
Author(s):  
G. MIZUTANI ◽  
N. ISHIBASHI ◽  
S. NAKAMURA ◽  
T. SEKIYA ◽  
S. KURITA
Keyword(s):  
Band Gap ◽  
Previous Analysis ◽  
Second Harmonic ◽  
Anatase Tio2 ◽  
Phonon Energy ◽  
Sharp Rise ◽  
Sum Frequency ◽  
Bulk Band ◽  
Frequency Intensity

We have investigated electronic levels of the H 2 O /anatase TiO 2 (101) interface by optical second harmonic spectroscopy. We see a sharp rise of SH intensity above the SH phonon energy 2ℏω~3.6 eV . According to our previous analysis, the SH signal from this face originates mainly from the H 2 O/TiO 2 (101) interface. The sum frequency intensity also shows a rise at ℏω1+ℏω2~3.6 eV . Thus the observed sharp rise of the SH intensity is due to a resonance of an interface band gap at 3.6eV. The energy of this interface band gap is larger than that of the bulk band gap, 3.2eV.

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