scholarly journals Observation of bulk states and spin-polarized topological surface states in transition metal dichalcogenide Dirac semimetal candidate NiTe2

2019 ◽  
Vol 100 (19) ◽  
Author(s):  
Barun Ghosh ◽  
Debashis Mondal ◽  
Chia-Nung Kuo ◽  
Chin Shan Lue ◽  
Jayita Nayak ◽  
...  
Keyword(s):  
Transition Metal ◽  
Surface States ◽  
Transition Metal Dichalcogenide ◽  
Dirac Semimetal ◽  
Spin Polarized ◽  
Topological Surface

Large Damping Enhancement in Dirac‐Semimetal–Ferromagnetic‐Metal Layered Structures Caused by Topological Surface States

2021 ◽  
pp. 2008411
Author(s):  
Jinjun Ding ◽  
Chuanpu Liu ◽  
Yuejie Zhang ◽  
Vijaysankar Kalappattil ◽  
Rui Yu ◽  
...  
Keyword(s):  
Surface States ◽  
Layered Structures ◽  
Ferromagnetic Metal ◽  
Dirac Semimetal ◽  
Topological Surface

scholarly journals Deep tuning of photo-thermoelectricity in topological surface states

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Shouyuan Huang ◽  
Ireneusz Miotkowski ◽  
Yong P. Chen ◽  
Xianfan Xu
Keyword(s):  
Surface State ◽  
Spin Injection ◽  
Three Dimensional ◽  
Polarized Light ◽  
Surface States ◽  
Linear Dispersion ◽  
Circularly Polarized Light ◽  
Spin Polarized ◽  
Topological Surface ◽  
Topological Surface State

Abstract Three-dimensional topological insulators have been demonstrated in recent years, which possess intriguing gapless, spin-polarized Dirac states with linear dispersion only on the surface. The spin polarization of the topological surface states is also locked to its momentum, which allows controlling motion of electrons using optical helicity, i.e., circularly polarized light. The electrical and thermal transport can also be significantly tuned by the helicity-control of surface state electrons. Here, we report studies of photo-thermoelectric effect of the topological surface states in Bi2Te2Se thin films with large tunability using varied gate voltages and optical helicity. The Seebeck coefficient can be altered by more than five times compared to the case without spin injection. This deep tuning is originated from the optical helicity-induced photocurrent which is shown to be enhanced, reduced, turned off, and even inverted due to the change of the accessed band structures by electrical gating. The helicity-selected topological surface state thus has a large effect on thermoelectric transport, demonstrating great opportunities for realizing helicity control of optoelectronic and thermal devices.

scholarly journals Origin of spin-polarized photocurrents in the topological surface states of Bi2Se3

2018 ◽  
Vol 98 (15) ◽  
Author(s):  
A. S. Ketterl ◽  
S. Otto ◽  
M. Bastian ◽  
B. Andres ◽  
C. Gahl ◽  
...  
Keyword(s):  
Surface States ◽  
Spin Polarized ◽  
Topological Surface

scholarly journals Topological surface states in strained Dirac semimetal thin films

2020 ◽  
Vol 102 (15) ◽  
Author(s):  
Pablo Villar Arribi ◽  
Jian-Xin Zhu ◽  
Timo Schumann ◽  
Susanne Stemmer ◽  
Anton A. Burkov ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface States ◽  
Dirac Semimetal ◽  
Topological Surface

Anisotropy of the spin-polarized edge current in monolayer transition metal dichalcogenide zigzag nanoribbons

2020 ◽  
Vol 101 (19) ◽  
Author(s):  
J. H. Correa ◽  
A. C. Dias ◽  
L. Villegas-Lelovsky ◽  
Jiyong Fu ◽  
Leonor Chico ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Dichalcogenide ◽  
Edge Current ◽  
Spin Polarized

scholarly journals Dimensional crossover and band topology evolution in ultrathin semimetallic NiTe2 films

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Joseph A. Hlevyack ◽  
Liang-Ying Feng ◽  
Meng-Kai Lin ◽  
Rovi Angelo B. Villaos ◽  
Ro-Ya Liu ◽  
...  
Keyword(s):  
Film Thickness ◽  
Ultrathin Films ◽  
Molecular Beam ◽  
Surface States ◽  
Single Layer ◽  
Dirac Fermions ◽  
Dirac Semimetal ◽  
Emergent Phenomena ◽  
Device Applications ◽  
Topological Surface

AbstractNickel ditelluride (NiTe2), a recently discovered Type-II Dirac semimetal with topological Dirac fermions near the Fermi energy, is expected to exhibit strong thickness-mediated electronic tunability and intrinsic two-gap superconductivity in the single-layer limit. Realizing such intriguing phenomena requires the fabrication of ultrathin NiTe2 films and an understanding of the underlying physics that is still under debate. By conducting experimental band mappings of ultrathin films prepared with molecular beam epitaxy, we reveal spectroscopic evidence for the dimensionality crossover of single-crystalline ultrathin NiTe2 films as a function of film thickness. As the film thickness increases from one to five layers, the gap in the conical topological surface states closes. Comparisons of experimental to first-principles results also highlight difficulties in fabricating atomically smooth single-layer NiTe2 films. Our results not only provide further impetus for studying emergent phenomena in NiTe2 but also underscore the limitations of fabricating NiTe2 films for device applications.

scholarly journals Deciphering asymmetric charge transfer at transition metal dichalcogenide–graphene interface by helicity-resolved ultrafast spectroscopy

2021 ◽  
Vol 7 (34) ◽  
pp. eabg2999
Author(s):  
Hongzhi Zhou ◽  
Yuzhong Chen ◽  
Haiming Zhu
Keyword(s):  
Charge Transfer ◽  
Transition Metal ◽  
Ultrafast Spectroscopy ◽  
Spin Dynamics ◽  
Hole Injection ◽  
Transition Metal Dichalcogenide ◽  
Transfer Processes ◽  
Spin Polarized ◽  
Graphene Interface ◽  
Interfacial Charge

Transition metal dichalcogenide (TMD)/graphene (Gr) heterostructures constitute a key component for two-dimensional devices. The operation of TMD/Gr devices relies on interfacial charge/energy transfer processes, which remains unclear and challenging to unravel. Fortunately, the coupled spin and valley index in TMDs adds a new degree of freedom to the charges and, thus, another dimension to spectroscopy. Here, by helicity-resolved ultrafast spectroscopy, we find that photoexcitation in TMDs transfers to graphene by asynchronous charge transfer, with one type of charge transferring in the order of femtoseconds and the other in picoseconds. The rate correlates well with energy offset between TMD and graphene, regardless of compositions and charge species. Spin-polarized hole injection or long-lived polarized hole can be achieved with deliberately designed heterostructures. This study shows helicity-resolved ultrafast spectroscopy as a powerful and facile approach to reveal the fundamental and complex charge/spin dynamics in TMD-based heterostructures, paving the way toward valleytronic and optoelectronic applications.

scholarly journals A Review of Topological Semimetal Phases in Photonic Artificial Microstructures

2021 ◽  
Vol 9 ◽  
Author(s):  
Boyang Xie ◽  
Hui Liu ◽  
Haonan Wang ◽  
Hua Cheng ◽  
Jianguo Tian ◽  
...  
Keyword(s):  
Photonic Crystals ◽  
Electromagnetic Waves ◽  
Three Dimensional ◽  
Surface States ◽  
Band Structures ◽  
Nodal Lines ◽  
Anomalous Reflection ◽  
Spin Polarized ◽  
Topological Semimetal ◽  
Topological Surface

In the past few years, the concept of topological matter has inspired considerable research in broad areas of physics. In particular, photonic artificial microstructures like photonic crystals and metamaterials provide a unique platform to investigate topologically non-trivial physics in spin-1 electromagnetic fields. Three-dimensional (3D) topological semimetal band structures, which carry non-trivial topological charges, are fundamental to 3D topological physics. Here, we review recent progress in understanding 3D photonic topological semimetal phases and various approaches for realizing them, especially with photonic crystals or metamaterials. We review topological gapless band structures and topological surface states aroused from the non-trivial bulk topology. Weyl points, 3D Dirac points, nodal lines, and nodal surfaces of different types are discussed. We also demonstrate their application in coupling spin-polarized electromagnetic waves, anomalous reflection, vortex beams generation, bulk transport, and non-Hermitian effects.

P-type doping in 2M-WS2 for a complete phase diagram

2021 ◽  
Author(s):  
Chendong Zhao ◽  
Xiangli Che ◽  
Zhuang Zhang ◽  
Fu Qiang Huang
Keyword(s):  
Phase Diagram ◽  
Transition Metal ◽  
Physical Properties ◽  
Transition Metal Dichalcogenides ◽  
Surface States ◽  
Complete Phase Diagram ◽  
Metal Dichalcogenides ◽  
Topological Surface ◽  
P Type ◽  
New Phase

2M-WS2 as a new phase of transition metal dichalcogenides possesses many novel physical properties, such as superconductivity and topological surface states. The effect of n-type doping on the superconductivity of...

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