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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: The gap enhancement in the vicinity of the hot spots emphasizes the role of antiferromagnetic fluctuations and the similarity in the origin of superconductivity for electron- and hole-doped cuprates.
Abstract: Low energy polarized electronic Raman scattering of the electron-doped superconductor Nd2-x Ce x CuO4 ( x = 0.15, T(c) = 22 K) has revealed a nonmonotonic d(x(2)-y(2)) superconducting order parameter. It has a maximum gap of 4.4k(B)T(c) at Fermi surface intersections with an antiferromagnetic Brillouin zone (the "hot spots") and a smaller gap of 3.3k(B)T(c) at fermionic Brillouin zone boundaries. The gap enhancement in the vicinity of the hot spots emphasizes the role of antiferromagnetic fluctuations and the similarity in the origin of superconductivity for electron- and hole-doped cuprates.

104 citations

Journal ArticleDOI
TL;DR: In this article, the acoustic normal modes were derived and numerically evaluated for a cylindrical step-index fiber with both an infinite and a finite cladding, and it was found that the phonon population which contributes to the Brillouin backscattering spectrum is both narrower in range and shifted in frequency when compared to the corresponding case in the bulk medium.
Abstract: Brillouin scattering in single-mode optical fibers has been investigated both theoretically and experimentally for a 180\ifmmode^\circ\else\textdegree\fi{} scattering geometry and experimentally for a 90\ifmmode^\circ\else\textdegree\fi{} scattering angle. The acoustic normal modes were derived and numerically evaluated for a cylindrical step-index fiber with both an infinite and a finite cladding. It was found that the phonon population which contributes to the Brillouin back-scattering spectrum is both narrower in range and shifted in frequency when compared to the corresponding case in the bulk medium. Back-scattering experiments were performed which yielded the intrinsic phonon lifetime for the longitudinally polarized excitations which are responsible for stimulated Brillouin scattering in the core of a 1.5-\ensuremath{\mu}m (radius) fiber. Brillouin spectra were also observed at a scattering angle of 90\ifmmode^\circ\else\textdegree\fi{}, and the widths of the spectral components were interpreted in terms of nonconservation of wave vector along the radial direction in the acousto-optic interaction. The consequences of these results to stimulated Brillouin scattering in optical fibers are discussed.

104 citations

Journal ArticleDOI
TL;DR: In this article, a method that utilizes a dispersion-shifted fiber having compound compositions with different temperature coefficients in core to simultaneously measure the distributed strain and temperature based on Brillouin frequency shift was proposed and realized.
Abstract: We propose and realize a new method that utilizes a dispersion-shifted fiber having compound compositions with different temperature coefficients in core to simultaneously measure the distributed strain and temperature based on Brillouin frequency shift. In a 3682-m sensing length of large-effective-area nonzero dispersion-shifted fiber, a temperature resolution of 5/spl deg/C, a strain resolution of 60 /spl mu//spl epsi/, and a spatial resolution of 2 m are achieved simultaneously.

104 citations

Journal ArticleDOI
TL;DR: In this paper, the use of Raman spectroscopy to study twisted bilayer graphene (tBLG) is reviewed, and the θ-dependent effects of van Hove singularities in the electronic density of states and phonons in the interior of the graphene Brillouin zone are investigated.

104 citations

Journal ArticleDOI
TL;DR: It is shown that the neglected hydrogen zero-point motion ZPM, plays a key role at Lifshitz transitions, and a Feshbach-like resonance between a possible BEC-BCS condensate at Γ and the BCS condensates in different k-space spots is proposed.
Abstract: While 203 K high temperature superconductivity in H3S has been interpreted by BCS theory in the dirty limit here we focus on the effects of hydrogen zero-point-motion and the multiband electronic structure relevant for multigap superconductivity near Lifshitz transitions. We describe how the topology of the Fermi surfaces evolves with pressure giving different Lifshitz-transitions. A neck-disrupting Lifshitz-transition (type 2) occurs where the van Hove singularity, vHs, crosses the chemical potential at 210 GPa and new small 2D Fermi surface portions appear with slow Fermi velocity where the Migdal-approximation becomes questionable. We show that the neglected hydrogen zero-point motion ZPM, plays a key role at Lifshitz transitions. It induces an energy shift of about 600 meV of the vHs. The other Lifshitz-transition (of type 1) for the appearing of a new Fermi surface occurs at 130 GPa where new Fermi surfaces appear at the Γ point of the Brillouin zone here the Migdal-approximation breaks down and the zero-point-motion induces large fluctuations. The maximum Tc = 203 K occurs at 160 GPa where EF/ω0 = 1 in the small Fermi surface pocket at Γ. A Feshbach-like resonance between a possible BEC-BCS condensate at Γ and the BCS condensate in different k-space spots is proposed.

104 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023430
2022957
2021463
2020543
2019568
2018587