Related papers: Topological Fermi-arc surface state covered by flo…
A two-dimensional (2D) Weyl semimetal featuring a spin-polarized linear band dispersion and a nodal Fermi surface is a new topological phase of matter. It is a solid-state realization of Weyl fermions in an intrinsic 2D system. The…
Topological phases of matter exhibit phase transitions between distinct topological classes. These phase transitions are exotic in that they do not fall within the traditional Ginzburg-Landau paradigm but are instead associated with changes…
Motivated by recent experiments probing anomalous surface states of Dirac semimetals (DSMs) Na$_3$Bi and Cd$_3$As$_2$, we raise the question posed in the title. We find that, in marked contrast to Weyl semimetals, the gapless surface states…
High resolution laser-based angle-resolved photoemission measurements have been carried out on Sb(111) single crystal. Two kinds of Fermi surface sheets are observed that are derived from the topological surface states: one small hexagonal…
Rich topological phenomena, edge states and two types of corner states, are unveiled in a two-dimensional square-lattice dielectric photonic crystal without both $C_4$ and $M_{x(y)}$ symmetries. Specifically, non-trivial type-I corner…
Fermi arcs represent the surface states at the boundary of a three-dimensional topological semimetal with the vacuum, illustrating the notion of bulk-boundary correspondence playing out in real materials. Their special character is tied up…
We show that one-dimensional quasi-periodic optical lattice systems can exhibit edge states and topological phases which are generally believed to appear in two-dimensional systems. When the Fermi energy lies in gaps, the Fermi system on…
The topology of a topological material can be encoded in its surface states. These surface states can only be removed by a bulk topological quantum phase transition into a trivial phase. Here we use photoemission spectroscopy to image the…
We have performed electron transport and ARPES measurements on single crystals of transition metal dipnictide TaAs2 cleaved along the ($\overline{2}$ 0 1) surface which has the lowest cleavage energy. A Fourier transform of the Shubnikov-de…
Electrons can form a two-dimensional electron gas at metal surfaces, where lateral confinement leads to quantum-well states. Such states have been observed for highly itinerant electrons, but it remains an open question whether quantum-well…
The electronic structures and topological properties of transition metal dipnictides $XPn_2$ ($X$=Ta, Nb; $Pn$=P, As, Sb) have been systematically studied using first-principles calculations. In addition to small bulk Fermi surfaces, the…
Riemann surfaces are geometric constructions in complex analysis that may represent multi-valued holomorphic functions using multiple sheets of the complex plane. We show that the energy dispersion of surface states in topological…
Weyl semimetals are extraordinary systems where exotic phenomena such as Fermi arcs, pseudo-gauge fields and quantum anomalies arise from topological band degeneracy in crystalline solids for electrons and metamaterials for photons and…
The quantum behaviour of electrons in materials lays the foundation for modern electronic and information technology. Quantum materials with novel electronic and optical properties have been proposed as the next frontier, but much remains…
We present first-time measurements of the Fermi surface and low-energy electronic structure of intermetallic compounds Gd2PdSi3 and Tb2PdSi3 by means of angle-resolved photoelectron spectroscopy (ARPES). Both materials possess a flower-like…
Lithium, a prototypical simple metal under ambient conditions, has a surprisingly rich phase diagram under pressure, taking up several structures with reduced symmetry, low coordination numbers, and even semiconducting character with…
The quantum Hall effect is usually observed in 2D systems. We show that the Fermi arcs can give rise to a distinctive 3D quantum Hall effect in topological semimetals. Because of the topological constraint, the Fermi arc at a single surface…
We discover three-dimensional intertwined Weyl phases, by developing a theory to create topological phases. The theory is based on intertwining existing topological gapped and gapless phases protected by the same crystalline symmetry. The…
It has been noted that certain surfaces of Weyl semimetals have bound states forming open Fermi arcs, which are never seen in typical metallic states. We show that the Fermi arcs enable them to support an even more exotic surface state with…
The Weyl semimetal phase is a recently discovered topological quantum state of matter characterized by the presence of topologically protected degeneracies near the Fermi level. These degeneracies are the source of exotic phenomena,…