scholarly journals Fermi-arc diversity on surface terminations of the magnetic Weyl semimetal Co3Sn2S2

Science ◽  
2019 ◽  
Vol 365 (6459) ◽  
pp. 1286-1291 ◽  
Author(s):  
Noam Morali ◽  
Rajib Batabyal ◽  
Pranab Kumar Nag ◽  
Enke Liu ◽  
Qiunan Xu ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Time Reversal ◽  
Surface States ◽  
Time Reversal Symmetry ◽  
Fermi Arc ◽  
Weyl Semimetal ◽  
Fermi Arcs ◽  
Bulk Surface ◽  
Weyl Semimetals ◽  
Node Connectivity

Bulk–surface correspondence in Weyl semimetals ensures the formation of topological “Fermi arc” surface bands whose existence is guaranteed by bulk Weyl nodes. By investigating three distinct surface terminations of the ferromagnetic semimetal Co3Sn2S2, we verify spectroscopically its classification as a time-reversal symmetry-broken Weyl semimetal. We show that the distinct surface potentials imposed by three different terminations modify the Fermi-arc contour and Weyl node connectivity. On the tin (Sn) surface, we identify intra–Brillouin zone Weyl node connectivity of Fermi arcs, whereas on cobalt (Co) termination, the connectivity is across adjacent Brillouin zones. On the sulfur (S) surface, Fermi arcs overlap with nontopological bulk and surface states. We thus resolve both topologically protected and nonprotected electronic properties of a Weyl semimetal.

scholarly journals Higher-Order Semimetals and Chiral Hinge States in Topolectrical Circuit Model

2021 ◽  
Author(s):  
S M Rafi-Ul-Islam ◽  
Zhuo Bin Siu ◽  
Mansoor Jalil
Keyword(s):  
Magnetic Field ◽  
Time Reversal ◽  
Higher Order ◽  
Circuit Model ◽  
Second Order ◽  
Time Reversal Symmetry ◽  
Fermi Arc ◽  
Dirac Semimetal ◽  
Chiral Phases ◽  
Weyl Semimetals

Abstract We propose a 3D topolectrical (TE) network that can be tuned to realize various higher-order topological gapless and chiral phases. We first study a higher-order Dirac semimetal phase that exhibits a hinge-like Fermi arc linking the Dirac points. This circuit can be extended to host highly tunable first- and second-order Weyl semimetals phases by introducing a non-reciprocal resistive coupling in the x − y plane that breaks time reversal symmetry. The first- and second-order Weyl points are connected by zero-admittance surface and hinge states, respectively. We also study the emergence of first- and second-order chiral modes induced by resistive couplings between similar nodes in the z-direction. These modes respectively occur in the midgap of the surface and hinge admittance bands in our circuit model without the need for any external magnetic field.

scholarly journals Cubic 3D Chern photonic insulators with orientable large Chern vectors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chiara Devescovi ◽  
Mikel García-Díez ◽  
Iñigo Robredo ◽  
María Blanco de Paz ◽  
Jon Lasa-Alonso ◽  
...  
Keyword(s):  
Time Reversal ◽  
Degrees Of Freedom ◽  
Surface States ◽  
Magnetic Response ◽  
Time Reversal Symmetry ◽  
General Strategy ◽  
Topological Phases ◽  
Magnetization Axis ◽  
Opening Up ◽  
Internal Symmetries

AbstractTime Reversal Symmetry (TRS) broken topological phases provide gapless surface states protected by topology, regardless of additional internal symmetries, spin or valley degrees of freedom. Despite the numerous demonstrations of 2D topological phases, few examples of 3D topological systems with TRS breaking exist. In this article, we devise a general strategy to design 3D Chern insulating (3D CI) cubic photonic crystals in a weakly TRS broken environment with orientable and arbitrarily large Chern vectors. The designs display topologically protected chiral and unidirectional surface states with disjoint equifrequency loops. The resulting crystals present the following characteristics: First, by increasing the Chern number, multiple surface states channels can be supported. Second, the Chern vector can be oriented along any direction simply changing the magnetization axis, opening up larger 3D CI/3D CI interfacing possibilities as compared to 2D. Third, by lowering the TRS breaking requirements, the system is ideal for realistic photonic applications where the magnetic response is weak.

scholarly journals Effect of magnetic field on the hydrogen evolution activity using non-magnetic Weyl semimetal catalysts

2020 ◽  
Vol 49 (11) ◽  
pp. 3398-3402 ◽  
Author(s):  
Uttam Gupta ◽  
Catherine R. Rajamathi ◽  
Nitesh Kumar ◽  
Guowei Li ◽  
Yan Sun ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electronic Properties ◽  
Hydrogen Evolution ◽  
Weyl Semimetal ◽  
Weyl Semimetals ◽  
The Magnetic Field

The magnetic field alters the rate of photochemical hydrogen evolution in Weyl semimetals by influencing its electronic properties.

scholarly journals Phase diagrams of superconducting topological surface states

2021 ◽  
Vol 24 (4) ◽  
pp. 43701
Author(s):  
W. Zhao ◽  
L. Ding ◽  
B. Zhou ◽  
J. Wu ◽  
Y. Bai ◽  
...  
Keyword(s):  
Phase Diagrams ◽  
Time Reversal ◽  
Mirror Symmetry ◽  
Surface States ◽  
Time Reversal Symmetry ◽  
And Topology ◽  
Topological Surface ◽  
Iron Based ◽  
Crystalline Symmetry

In this paper, we present a detailed study on the phase diagrams of superconducting topological surface states, especially, focusing on the interplay between crystalline symmetry and topology of the effective BdG Hamiltonian. We show that for the 4 x 4 kinematic Hamiltonian of the normal state, a mirror symmetry M can be defined, and for the M-odd pairings, the classification of the 8 x 8 BdG Hamiltonian is ℤ⊕ℤ, and the time-reversal symmetry is broken intrinsically. The topological non-trivial phase can support chiral Majorana edge modes, and can be realized in the thin films of iron-based superconductor such as FeSeTe.

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