scholarly journals Robust edge photocurrent response on layered type II Weyl semimetal WTe2

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Qinsheng Wang ◽  
Jingchuan Zheng ◽  
Yuan He ◽  
Jin Cao ◽  
Xin Liu ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Surface States ◽  
Separation Mechanism ◽  
Current Response ◽  
Type Ii ◽  
Nonlinear Optical Effect ◽  
Linear Dispersion ◽  
Weyl Semimetal ◽  
Quantum Materials ◽  
A Charge

AbstractPhotosensing and energy harvesting based on exotic properties of quantum materials and new operation principles have great potential to break the fundamental performance limit of conventional photodetectors and solar cells. Weyl semimetals have demonstrated novel optoelectronic properties that promise potential applications in photodetection and energy harvesting arising from their gapless linear dispersion and Berry field enhanced nonlinear optical effect at the vicinity of Weyl nodes. In this work, we demonstrate robust photocurrent generation at the edge of Td-WTe2, a type-II Weyl semimetal, due to crystalline-symmetry breaking along certain crystal fracture directions and possibly enhanced by robust fermi-arc type surface states. This edge response is highly generic and arises universally in a wide class of quantum materials with similar crystal symmetries. The robust and generic edge current response provides a charge separation mechanism for photosensing and energy harvesting over broad wavelength range.

scholarly journals Quasiparticle interference of surface states in the type-II Weyl semimetal WTe2

2017 ◽  
Vol 96 (16) ◽  
Author(s):  
Wenhan Zhang ◽  
Quansheng Wu ◽  
Lunyong Zhang ◽  
Sang-Wook Cheong ◽  
Alexey A. Soluyanov ◽  
...  
Keyword(s):  
Surface States ◽  
Type Ii ◽  
Quasiparticle Interference ◽  
Weyl Semimetal

scholarly journals Surface superconductivity in the type II Weyl semimetal TaIrTe4

2019 ◽  
Vol 7 (3) ◽  
pp. 579-587 ◽  
Author(s):  
Ying Xing ◽  
Zhibin Shao ◽  
Jun Ge ◽  
Jiawei Luo ◽  
Jinhua Wang ◽  
...  
Keyword(s):  
Upper Critical Field ◽  
Surface States ◽  
P Wave ◽  
Scanning Tunneling ◽  
Type Ii ◽  
Surface Superconductivity ◽  
Weyl Semimetal ◽  
Ultralow Temperature ◽  
Transport Measurements ◽  
Majorana Modes

Abstract The search for unconventional superconductivity in Weyl semimetal materials is currently an exciting pursuit, since such superconducting phases could potentially be topologically non-trivial and host exotic Majorana modes. The layered material TaIrTe4 is a newly predicted time-reversal invariant type II Weyl semimetal with the minimum number of Weyl points. Here, we report the discovery of surface superconductivity in Weyl semimetal TaIrTe4. Our scanning tunneling microscopy/spectroscopy (STM/STS) visualizes Fermi arc surface states of TaIrTe4 that are consistent with the previous angle-resolved photoemission spectroscopy results. By a systematic study based on STS at ultralow temperature, we observe uniform superconducting gaps on the sample surface. The superconductivity is further confirmed by electrical transport measurements at ultralow temperature, with an onset transition temperature (Tc) up to 1.54 K being observed. The normalized upper critical field h*(T/Tc) behavior and the stability of the superconductivity against the ferromagnet indicate that the discovered superconductivity is unconventional with the p-wave pairing. The systematic STS, and thickness- and angular-dependent transport measurements reveal that the detected superconductivity is quasi-1D and occurs in the surface states. The discovery of the surface superconductivity in TaIrTe4 provides a new novel platform to explore topological superconductivity and Majorana modes.

scholarly journals A strongly robust type II Weyl fermion semimetal state in Ta3S2

2016 ◽  
Vol 2 (6) ◽  
pp. e1600295 ◽  
Author(s):  
Guoqing Chang ◽  
Su-Yang Xu ◽  
Daniel S. Sanchez ◽  
Shin-Ming Huang ◽  
Chi-Cheng Lee ◽  
...  
Keyword(s):  
Surface States ◽  
Insulator Transition ◽  
Type Ii ◽  
Weyl Semimetal ◽  
Tantalum Sulfide ◽  
Weyl Semimetals ◽  
Device Applications ◽  
Metal To Insulator Transition ◽  
Weyl Fermion ◽  
Topological Metal

Weyl semimetals are of great interest because they provide the first realization of the Weyl fermion, exhibit exotic quantum anomalies, and host Fermi arc surface states. The separation between Weyl nodes of opposite chirality gives a measure of the robustness of the Weyl semimetal state. To exploit the novel phenomena that arise from Weyl fermions in applications, it is crucially important to find robust separated Weyl nodes. We propose a methodology to design robust Weyl semimetals with well-separated Weyl nodes. Using this methodology as a guideline, we search among the material parameter space and identify by far the most robust and ideal Weyl semimetal candidate in the single-crystalline compound tantalum sulfide (Ta3S2) with new and novel properties beyond TaAs. Crucially, our results show that Ta3S2has the largestk-space separation between Weyl nodes among known Weyl semimetal candidates, which is about twice larger than the measured value in TaAs and 20 times larger than the predicted value in WTe2. Moreover, all Weyl nodes in Ta3S2are of type II. Therefore, Ta3S2is a type II Weyl semimetal. Furthermore, we predict that increasing the lattice by <4% can annihilate all Weyl nodes, driving a novel topological metal-to-insulator transition from a Weyl semimetal state to a topological insulator state. The robust type II Weyl semimetal state and the topological metal-to-insulator transition in Ta3S2are potentially useful in device applications. Our methodology can be generally applied to search for new Weyl semimetals.

scholarly journals Coexistence of type-II and type-IV Dirac fermions in SrAgBi

2021 ◽  
pp. 2150181
Author(s):  
Tian-Chi Ma ◽  
Jing-Nan Hu ◽  
Yuan Chen ◽  
Lei Shao ◽  
Xian-Ru Hu ◽  
...  
Keyword(s):  
High Energy Physics ◽  
Surface States ◽  
High Energy ◽  
Dirac Fermion ◽  
Dirac Fermions ◽  
Type Ii ◽  
Linear Dispersion ◽  
Space Groups ◽  
Type Iv ◽  
Poincaré Symmetry

Relativistic massless Weyl and Dirac fermions have isotropic and linear dispersion relations to maintain Poincaré symmetry, which is the most basic symmetry in high-energy physics. The situation in condensed matter physics is less constrained; only certain subgroups of Poincaré symmetry — the 230 space groups that exist in 3D lattices — need be respected. Then, the free fermionic excitations that have no high-energy analogues could exist in solid state systems. Here, We discovered a type of nonlinear Dirac fermion without high-energy analogue in SrAgBi and named it type-IV Dirac fermion. The type-IV Dirac fermion has a nonlinear dispersion relationship and is similar to the type-II Dirac fermion, which has electron pocket and hole pocket. The effective model for the type-IV Dirac fermion is also found. It is worth pointing out that there is a type-II Dirac fermion near this new Dirac fermion. So we used two models to describe the coexistence of these two Dirac fermions. Topological surface states of these two Dirac points are also calculated. We envision that our findings will stimulate researchers to study novel physics of type-IV Dirac fermions, as well as the interplay of type-II and type-IV Dirac fermions.

SIn2Te/TeIn2Se: a type-II heterojunction as water-splitting photocatalyst with high solar energy harvesting

2021 ◽  
Author(s):  
Peishen Shang ◽  
Chunxiao Zhang ◽  
Mengshi Zhou ◽  
Chaoyu He ◽  
Tao Ouyang ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Solar Energy ◽  
Water Splitting ◽  
First Principles ◽  
Type Ii ◽  
Two Dimensional ◽  
First Principles Calculations ◽  
Solar Energy Harvesting ◽  
Renewable Hydrogen

Searching for photocatalysts is crucial for the production of renewable hydrogen from water. Two-dimensional (2D) vdW heterojunctions show great potential. Using first- principles calculations within the HSE06 functional, we propose...

scholarly journals Nonsaturating Magnetoresistance and Nontrivial Band Topology of Type‐II Weyl Semimetal NbIrTe 4

2019 ◽  
Vol 5 (8) ◽  
pp. 1900250 ◽  
Author(s):  
Wei Zhou ◽  
Bin Li ◽  
Chun Qiang Xu ◽  
Maarten R. Delft ◽  
Yu Ge Chen ◽  
...  
Keyword(s):  
Type Ii ◽  
Weyl Semimetal

scholarly journals Magnetoresistance and scaling laws in type-II Weyl semimetal WP2

2021 ◽  
pp. 413062
Author(s):  
V. Nagpal ◽  
K.S. Jat ◽  
S. Patnaik
Keyword(s):  
Scaling Laws ◽  
Type Ii ◽  
Weyl Semimetal

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.

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