Topic
Brillouin zone
About: Brillouin zone is a research topic. Over the lifetime, 13849 publications have been published within this topic receiving 383077 citations.
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TL;DR: Topological flat bands are observed near the Fermi level in a kagome metal CoSn, with flat bands as well as Dirac bands originating from 3d orbitals in a frustrated kagom geometry demonstrated to be frustration-driven.
Abstract: Electronic flat bands in momentum space, arising from strong localization of electrons in real space, are an ideal stage to realize strongly-correlated phenomena. Theoretically, the flat bands can naturally arise in certain geometrically frustrated lattices, often with nontrivial topology if combined with spin-orbit coupling. Here, we report the observation of topological flat bands in frustrated kagome metal CoSn, using angle-resolved photoemission spectroscopy and band structure calculations. Throughout the entire Brillouin zone, the bandwidth of the flat band is suppressed by an order of magnitude compared to the Dirac bands originating from the same orbitals. The frustration-driven nature of the flat band is directly confirmed by the chiral d-orbital texture of the corresponding real-space Wannier functions. Spin-orbit coupling opens a large gap of 80 meV at the quadratic touching point between the Dirac and flat bands, endowing a nonzero Z2 invariant to the flat band. These findings demonstrate that kagome-derived flat bands are a promising platform for novel emergent phases of matter at the confluence of strong correlation and topology. The experimental realization of lattice-born flat bands with nontrivial topology has been elusive. Here, the authors observe topological flat bands near the Fermi level in a kagome metal CoSn, with flat bands as well as Dirac bands originating from 3d orbitals in a frustrated kagome geometry.
139 citations
TL;DR: In this paper, the authors studied the energy transport in chains of noncontacting metal nanoparticles within an exactly solvable model, where the transport is mediated by the electromagnetic interactions between plasmons confined to the individual nanoparticles.
Abstract: Electromagnetic energy transport in chains of noncontacting metal nanoparticles is studied within an exactly solvable model. The transport is mediated by the retarded electromagnetic interactions between plasmons confined to the individual nanoparticles and therefore self-consistently accounts for spontaneous emission on the same footing as the transport; the propagating hybrid plasmonic-electromagnetic modes of the chain are known as plasmon polaritons. Dark modes are found in the first Brillouin zone when the excitation wavelength is greater than the resonant optical wavelength, suggesting the possibility of the suppression of radiative losses. Nearest-neighbor tight-binding models are shown to be of limited validity.
139 citations
TL;DR: In this paper, the authors introduce the notion of topological order in insulators as an obstruction to define the Bloch wave functions over the whole Brillouin Zone using a single phase convention.
139 citations
TL;DR: In this article, it was shown that if aluminum had one valence electron, its spin relaxation would be slower by nearly two orders of magnitude, which not only solves a longstanding experimental puzzle, but also provides a way of tailoring spin dynamics of electrons in a conduction band.
Abstract: Relaxation of electronic spins in metals is significantly enhanced whenever a Fermi surface crosses Brillouin zone boundaries, special symmetry points, or lines of accidental degeneracy. A realistic calculation shows that if aluminum had one valence electron, its spin relaxation would be slower by nearly two orders of magnitude. This not only solves a longstanding experimental puzzle, but also provides a way of tailoring spin dynamics of electrons in a conduction band.
139 citations
TL;DR: A multi-mode optomechanical waveguide is used to create stimulated Brillouin scattering between light-fields guided in distinct spatial modes of an integrated waveguide for the first time, which decouples Stokes and anti-Stokes processes to enable single-sideband amplification and dynamics that permit near-unity power conversion.
Abstract: Brillouin nonlinearities-which result from coupling between photons and acoustic phonons-are exceedingly weak in conventional nanophotonic silicon waveguides. Only recently have Brillouin interactions been transformed into the strongest and most tailorable nonlinear interactions in silicon using a new class of optomechanical waveguides that control both light and sound. In this paper, we use a multi-mode optomechanical waveguide to create stimulated Brillouin scattering between light-fields guided in distinct spatial modes of an integrated waveguide for the first time. This interaction, termed stimulated inter-modal Brillouin scattering, decouples Stokes and anti-Stokes processes to enable single-sideband amplification and dynamics that permit near-unity power conversion. Using integrated mode multiplexers to address separate optical modes, we show that circulators and narrowband filters are not necessary to separate pump and signal waves. We also demonstrate net optical amplification and Brillouin energy transfer as the basis for flexible on-chip light sources, amplifiers, nonreciprocal devices and signal-processing technologies.
139 citations