scholarly journals Topological flat band, Dirac fermions and quantum spin Hall phase in 2D Archimedean lattices

2019 ◽  
Vol 21 (40) ◽  
pp. 22344-22350 ◽  
Author(s):  
F. Crasto de Lima ◽  
Gerson J. Ferreira ◽  
R. H. Miwa
Keyword(s):  
Electronic Structure ◽  
Electronic Properties ◽  
Quantum Spin ◽  
Flat Band ◽  
Type I ◽  
Topological Phases ◽  
Dirac Fermions ◽  
Flat Bands ◽  
Quantum Spin Hall

We've constructed a guide to the electronic properties and topological phases of Archimedean lattices. Within these lattices, a rich electronic structure emerges forming type-I and II Dirac fermions, topological flat bands and high-degeneracy points.

scholarly journals Electronic structure of the quantum spin Hall parent compound CdTe and related topological issues

2014 ◽  
Vol 90 (20) ◽  
Author(s):  
Jie Ren ◽  
Guang Bian ◽  
Li Fu ◽  
Chang Liu ◽  
Tao Wang ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Parent Compound ◽  
Quantum Spin ◽  
Quantum Spin Hall

scholarly journals Observation of the quantum spin Hall effect up to 100 kelvin in a monolayer crystal

Science ◽  
2018 ◽  
Vol 359 (6371) ◽  
pp. 76-79 ◽  
Author(s):  
Sanfeng Wu ◽  
Valla Fatemi ◽  
Quinn D. Gibson ◽  
Kenji Watanabe ◽  
Takashi Taniguchi ◽  
...  
Keyword(s):  
Hall Effect ◽  
Time Reversal ◽  
Quantum Spin ◽  
Spin Hall Effect ◽  
Semiconductor Heterostructures ◽  
Topological Phases ◽  
Two Dimensional ◽  
Quantum Spin Hall Effect ◽  
Elastic Backscattering ◽  
Quantum Spin Hall

A variety of monolayer crystals have been proposed to be two-dimensional topological insulators exhibiting the quantum spin Hall effect (QSHE), possibly even at high temperatures. Here we report the observation of the QSHE in monolayer tungsten ditelluride (WTe2) at temperatures up to 100 kelvin. In the short-edge limit, the monolayer exhibits the hallmark transport conductance, ~e2/h per edge, where e is the electron charge and h is Planck’s constant. Moreover, a magnetic field suppresses the conductance, and the observed Zeeman-type gap indicates the existence of a Kramers degenerate point and the importance of time-reversal symmetry for protection from elastic backscattering. Our results establish the QSHE at temperatures much higher than in semiconductor heterostructures and allow for exploring topological phases in atomically thin crystals.

scholarly journals Deconfinement of Mott localized electrons into topological and spin–orbit-coupled Dirac fermions

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
José M. Pizarro ◽  
Severino Adler ◽  
Karim Zantout ◽  
Thomas Mertz ◽  
Paolo Barone ◽  
...  
Keyword(s):  
Phase Transition ◽  
Tricritical Point ◽  
Density Wave ◽  
Wave Pattern ◽  
Quantum Spin ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Dirac Fermions ◽  
Spin Orbit ◽  
Quantum Spin Hall

Abstract The interplay of electronic correlations, spin–orbit coupling and topology holds promise for the realization of exotic states of quantum matter. Models of strongly interacting electrons on honeycomb lattices have revealed rich phase diagrams featuring unconventional quantum states including chiral superconductivity and correlated quantum spin Hall insulators intertwining with complex magnetic order. Material realizations of these electronic states are, however, scarce or inexistent. In this work, we propose and show that stacking 1T-TaSe2 into bilayers can deconfine electrons from a deep Mott insulating state in the monolayer to a system of correlated Dirac fermions subject to sizable spin–orbit coupling in the bilayer. 1T-TaSe2 develops a Star-of-David charge density wave pattern in each layer. When the Star-of-David centers belonging to two adyacent layers are stacked in a honeycomb pattern, the system realizes a generalized Kane–Mele–Hubbard model in a regime where Dirac semimetallic states are subject to significant Mott–Hubbard interactions and spin–orbit coupling. At charge neutrality, the system is close to a quantum phase transition between a quantum spin Hall and an antiferromagnetic insulator. We identify a perpendicular electric field and the twisting angle as two knobs to control topology and spin–orbit coupling in the system. Their combination can drive it across hitherto unexplored grounds of correlated electron physics, including a quantum tricritical point and an exotic first-order topological phase transition.

scholarly journals Design and realization of topological Dirac fermions on a triangular lattice

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Maximilian Bauernfeind ◽  
Jonas Erhardt ◽  
Philipp Eck ◽  
Pardeep K. Thakur ◽  
Judith Gabel ◽  
...  
Keyword(s):  
Triangular Lattice ◽  
Quantum Spin ◽  
Spin Orbit Coupling ◽  
Dirac Fermions ◽  
Spin Orbit ◽  
Hexagonal Symmetry ◽  
Tunneling Microscopy ◽  
Heavy Atoms ◽  
Strong Spin ◽  
Quantum Spin Hall

AbstractLarge-gap quantum spin Hall insulators are promising materials for room-temperature applications based on Dirac fermions. Key to engineer the topologically non-trivial band ordering and sizable band gaps is strong spin-orbit interaction. Following Kane and Mele’s original suggestion, one approach is to synthesize monolayers of heavy atoms with honeycomb coordination accommodated on templates with hexagonal symmetry. Yet, in the majority of cases, this recipe leads to triangular lattices, typically hosting metals or trivial insulators. Here, we conceive and realize “indenene”, a triangular monolayer of indium on SiC exhibiting non-trivial valley physics driven by local spin-orbit coupling, which prevails over inversion-symmetry breaking terms. By means of tunneling microscopy of the 2D bulk we identify the quantum spin Hall phase of this triangular lattice and unveil how a hidden honeycomb connectivity emerges from interference patterns in Bloch px ± ipy-derived wave functions.

A New Type of Large‐Gap Quantum Spin Hall Insulator Material ZrSe 5

2021 ◽  
Author(s):  
Xing Wang ◽  
Wenhui Wan ◽  
Yanfeng Ge ◽  
Jun Li ◽  
Yong Liu
Keyword(s):  
Quantum Spin ◽  
New Type ◽  
Quantum Spin Hall

scholarly journals Ternary wurtzite CaAgBi materials family: A playground for essential and accidental, type-I and type-II Dirac fermions

2017 ◽  
Vol 1 (4) ◽  
Author(s):  
Cong Chen ◽  
Shan-Shan Wang ◽  
Lei Liu ◽  
Zhi-Ming Yu ◽  
Xian-Lei Sheng ◽  
...  
Keyword(s):  
Type I ◽  
Dirac Fermions ◽  
Type Ii
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