Hourglass Weyl and Dirac nodal line phonons, and drumhead-like and torus phonon surface states in orthorhombic-type KCuS

2022 ◽  
Author(s):  
Jianhua Wang ◽  
Hongkuan Yuan ◽  
Ying Liu ◽  
Feng Zhou ◽  
Xiaotian Wang ◽  
...  
Keyword(s):  
Surface States ◽  
Nodal Line ◽  
Symmetry Analysis ◽  
Electronic Systems

In parallel to electronic systems, the concept of topology has been extended to phonons, which has led to the birth of topological phonons. In this Letter, based on symmetry analysis...

scholarly journals Double-bowl state in photonic Dirac nodal line semimetal

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Mengying Hu ◽  
Ye Zhang ◽  
Xi Jiang ◽  
Tong Qiao ◽  
Qiang Wang ◽  
...  
Keyword(s):  
Surface States ◽  
Nodal Line ◽  
Electronic Systems ◽  
Nodal Lines ◽  
Spectrum Range ◽  
The Past ◽  
Topological Materials ◽  
Classical Waves ◽  
Topological Semimetals ◽  
Polarized Surface

AbstractThe past decade has seen a proliferation of topological materials for both insulators and semimetals in electronic systems and classical waves. Topological semimetals exhibit topologically protected band degeneracies, such as nodal points and nodal lines. Dirac nodal line semimetals (DNLS), which own four-fold line degeneracy, have drawn particular attention. DNLSs have been studied in electronic systems but there is no photonic DNLS. Here in this work, we provide a new mechanism, which is unique for photonic systems to investigate a stringent photonic DNLS. When truncated, the photonic DNLS exhibits double-bowl states (DBS), which comprise two sets of perpendicularly polarized surface states. In sharp contrast to nondegenerate surface states in other photonic systems, here the two sets of surface states are almost degenerate over the whole-spectrum range. The DBS and the bulk Dirac nodal ring (DNR) dispersion along the relevant directions, are experimentally resolved.

scholarly journals Magnetism-induced topological transition in EuAs3

2020 ◽  
Author(s):  
Erjian Cheng ◽  
Wei Xia ◽  
Jie Xu ◽  
Chengwei Wang ◽  
Chuanying Xi ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Berry Phase ◽  
Magnetic Moments ◽  
Surface States ◽  
Nodal Line ◽  
Chiral Anomaly ◽  
Topological Transition ◽  
Spin Polarized ◽  
Exotic Physics ◽  
Topological Semimetals

Abstract The nature of the interaction between magnetism and topology in magnetic topological semimetals remains mysterious, but may be expected to lead to a variety of novel physics. We present ab initio band calculations, electrical transport and angle-resolved photoemission spectroscopy (ARPES) measurements on the magnetic semimetal EuAs3, demonstrating a magnetism-induced topological transition from a topological nodal-line semimetal in the paramagnetic or the spin-polarized state to a topological massive Dirac metal in the antiferromagnetic (AFM) ground state at low temperature, featuring a pair of massive Dirac points, inverted bands and topological surface states on the (010) surface. Shubnikov-de Haas (SdH) oscillations in the AFM state identify nonzero Berry phase and a negative longitudinal magnetoresistance (n-LMR) induced by the chiral anomaly, confirming the topological nature predicted by band calculations. When magnetic moments are fully polarized by an external magnetic field, an unsaturated and extremely large magnetoresistance (XMR) of ∼ 2×105 % at 1.8 K and 28.3 T is observed, likely arising from topological protection. Consistent with band calculations for the spin-polarized state, four new bands in quantum oscillations different from those in the AFM state are discerned, of which two are topologically protected. Nodal-line structures at the Y point in the Brillouin zone (BZ) are proposed in both the spin-polarized and paramagnetic states, and the latter is proven by ARPES. Moreover, a temperature-induced Lifshitz transition accompanied by the emergence of a new band below 3 K is revealed. These results indicate that magnetic EuAs3 provides a rich platform to explore exotic physics arising from the interaction of magnetism with topology.

scholarly journals Hyperbolic Plasmons Propagate through a Nodal Metal

2022 ◽  
Author(s):  
Yinming Shao ◽  
Aaron Sternbach ◽  
Brian Kim ◽  
Andrey Rikhter ◽  
Xinyi Xu ◽  
...  
Keyword(s):  
Light Propagation ◽  
Near Infrared ◽  
Surface States ◽  
Nodal Line ◽  
Infrared Light ◽  
Energy Bands ◽  
Optical Wavelengths ◽  
Hyperbolic Waves ◽  
Optical Waveguiding

Abstract Metals are canonical plasmonic media at infrared and optical wavelengths allowing one to guide and manipulate light at sub-diffractional length scales. A special form of optical waveguiding is offered by highly anisotropic crystals revealing different signs of the dielectric function along orthogonal directions. These latter types of media are classified as hyperbolic and many crystalline insulators, semiconductors and artificial metal-based metamaterials belong to that class. Layered anisotropic metals are also anticipated to support hyperbolic waveguiding. Yet this behavior remains elusive primarily because interband processes introduce extreme losses and arrest light propagation. Here, we report on the observation of propagating hyperbolic waves in a prototypical layered nodal-line semimetal ZrSiSe. The unique electronic structure with touching energy bands at nodal points/lines suppresses losses and enables a hyperbolic regime at the telecommunications frequencies. The observed waveguiding in metallic ZrSiSe is a product of polaritonic hybridization between near-infrared light and long-lived nodal-line plasmons. By mapping the energy-momentum dispersion of the nodal-line hyperbolic modes in ZrSiSe we inquired into the role of additional screening associated with the surface states.

scholarly journals Weyl-like points from band inversions of spin-polarised surface states in NbGeSb

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
I. Marković ◽  
C. A. Hooley ◽  
O. J. Clark ◽  
F. Mazzola ◽  
M. D. Watson ◽  
...  
Keyword(s):  
Mirror Symmetry ◽  
Density Functional ◽  
Three Dimensional ◽  
Surface States ◽  
Nodal Line ◽  
Surface Band ◽  
Spin Orbital ◽  
Band Inversion ◽  
Topological Surface ◽  
Symmetry Protected

AbstractBand inversions are key to stabilising a variety of novel electronic states in solids, from topological surface states to the formation of symmetry-protected three-dimensional Dirac and Weyl points and nodal-line semimetals. Here, we create a band inversion not of bulk states, but rather between manifolds of surface states. We realise this by aliovalent substitution of Nb for Zr and Sb for S in the ZrSiS family of nonsymmorphic semimetals. Using angle-resolved photoemission and density-functional theory, we show how two pairs of surface states, known from ZrSiS, are driven to intersect each other near the Fermi level in NbGeSb, and to develop pronounced spin splittings. We demonstrate how mirror symmetry leads to protected crossing points in the resulting spin-orbital entangled surface band structure, thereby stabilising surface state analogues of three-dimensional Weyl points. More generally, our observations suggest new opportunities for engineering topologically and symmetry-protected states via band inversions of surface states.

scholarly journals Persistent optical gating of a topological insulator

2015 ◽  
Vol 1 (9) ◽  
pp. e1500640 ◽  
Author(s):  
Andrew L. Yeats ◽  
Yu Pan ◽  
Anthony Richardella ◽  
Peter J. Mintun ◽  
Nitin Samarth ◽  
...  
Keyword(s):  
Chemical Potential ◽  
Surface States ◽  
Optical Control ◽  
Electronic Systems ◽  
Optical Gating ◽  
Wide Range ◽  
Spin Polarized ◽  
Electrostatic Gating ◽  
Polarized Surface ◽  
Insulating Phase

The spin-polarized surface states of topological insulators (TIs) are attractive for applications in spintronics and quantum computing. A central challenge with these materials is to reliably tune the chemical potential of their electrons with respect to the Dirac point and the bulk bands. We demonstrate persistent, bidirectional optical control of the chemical potential of (Bi,Sb)2Te3thin films grown on SrTiO3. By optically modulating a space-charge layer in the SrTiO3substrates, we induce a persistent field effect in the TI films comparable to electrostatic gating techniques but without additional materials or processing. This enables us to optically pattern arbitrarily shapedp- andn-type regions in a TI, which we subsequently image with scanning photocurrent microscopy. The ability to optically write and erase mesoscopic electronic structures in a TI may aid in the investigation of the unique properties of the topological insulating phase. The gating effect also generalizes to other thin-film materials, suggesting that these phenomena could provide optical control of chemical potential in a wide range of ultrathin electronic systems.

scholarly journals Polaritonic Tamm states induced by cavity photons

Nanophotonics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 513-521 ◽  
Author(s):  
Charles A. Downing ◽  
Luis Martín-Moreno
Keyword(s):  
Surface States ◽  
Electronic Systems ◽  
Cross Sectional ◽  
Strong Light ◽  
One Dimensional ◽  
Dipole Interactions ◽  
Quantum Confinement Effects ◽  
New States ◽  
Ratio Scales ◽  
Periodic Chain

AbstractWe consider a periodic chain of oscillating dipoles, interacting via long-range dipole–dipole interactions, embedded inside a cuboid cavity waveguide. We show that the mixing between the dipolar excitations and cavity photons into polaritons can lead to the appearance of new states localized at the ends of the dipolar chain, which are reminiscent of Tamm surface states found in electronic systems. A crucial requirement for the formation of polaritonic Tamm states is that the cavity cross section is above a critical size. Above this threshold, the degree of localization of the Tamm states is highly dependent on the cavity size since their participation ratio scales linearly with the cavity cross-sectional area. Our findings may be important for quantum confinement effects in one-dimensional systems with strong light–matter coupling.

scholarly journals Ultrasonic nodal chains in topological granular metamaterials

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Aurélien Merkel ◽  
Johan Christensen
Keyword(s):  
Material Characterization ◽  
Condensed Matter ◽  
Three Dimensional ◽  
Surface States ◽  
Nodal Line ◽  
Topological Phases ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Ultrasonic Devices ◽  
Non Destructive

AbstractThree-dimensional (3D) Weyl and Dirac semimetals garner considerable attention in condensed matter physics due to the exploration of entirely new topological phases and related unconventional surface states. Nodal line and ring semimetals, on the other hand, can facilitate 3D band crossings characterized by nontrivial links such as coupled chains and knots that are protected by the underlying crystal symmetry. Experimental complexities and detrimental effects of the spin-orbit interaction, among others, pose great challenges for the advancement that can be overcome with other systems such as bosonic lattices. Here we demonstrate that a 3D mechanical metamaterial made of granular beads hosts multiple intersecting nodal rings in the ultrasonic regime. By unveiling these yet unseen classical topological phases, we discuss the resilience of the associated novel surface states that appear entirely unaffected to the type of crystal termination, making them a promising platform in ultrasonic devices for non-destructive testing and material characterization.

Symmetry Analysis of the Fermi Surface States of Sr2RuO4by Display-Type Photoelectron Spectroscopy

1999 ◽  
Vol 68 (4) ◽  
pp. 1398-1403 ◽  
Author(s):  
Taichi Okuda ◽  
Masato Kotsugi ◽  
Kan Nakatsuji ◽  
Masao Fujikawa ◽  
Shigemasa Suga ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Photoelectron Spectroscopy ◽  
Surface States ◽  
Symmetry Analysis ◽  
Display Type

scholarly journals Rich topological nodal line bulk states together with drum-head-like surface states in NaAlGe with anti-PbFCl type structure

2020 ◽  
Vol 23 ◽  
pp. 95-100 ◽  
Author(s):  
Xiaotian Wang ◽  
Guangqian Ding ◽  
Zhenxiang Cheng ◽  
Gokhan Surucu ◽  
Xiao-Lin Wang ◽  
...  
Keyword(s):  
Surface States ◽  
Nodal Line ◽  
Type Structure
Sign in / Sign up

Export Citation Format

Share Document