Brillouin zone

About: Brillouin zone is a research topic. Over the lifetime, 13849 publications have been published within this topic receiving 383077 citations.

Types of topological surface states in nodal noncentrosymmetric superconductors

Abstract: Nodal noncentrosymmetric superconductors have topologically nontrivial properties manifested by protected zero-energy surface states. Specifically, it was recently found that zero-energy surface flat bands of topological origin appear at their surface. We show that the presence of certain inversion-type lattice symmetries can give rise to additional topological features of the gap nodes, resulting in surface states forming one-dimensional arcs connecting the projections of two nodal rings. In addition, we demonstrate that Majorana surface states can appear at time-reversal-invariant momenta of the surface Brillouin zone, even when the system is not fully gapped in the bulk. Within a continuum theory we derive the topological invariants that protect these different types of zero-energy surface states. We independently derive general conditions for the existence of zero-energy surface bound states using the complementary quasiclassical scattering theory, explicitly taking into account the effects of spin-orbit splitting of the bands. We compute surface bound-state spectra for various crystal point-group symmetries and orbital-angular-momentum pairing states. Finally, we examine the signatures of the arc surface states and of the zero-energy surface flat bands in tunneling-conductance spectra and dicuss how topological phase transitions in noncentrosymmetric superconductors could be observed in experiments.

Remote spectroscopy for raman and brillouin scattering

Abstract: An apparatus and method for performing Raman and Brillouin spectroscopy remotely. A near-infrared laser is used to irradiate a sample of material to be analyzed. Optical fibers transmit incident radiation from a near-infrared radiation source to the sample, and transmit Raman and Brillouin scattered radiation from the sample to the detecting equipment. The incident radiation is carefully determined so as to avoid fluorescence and to limit optic fiber losses. The invention provides useful information with the use of an interferometer.

Experimental and numerical investigation of the SBS-threshold increase in an optical fiber by applying strain distributions

Abstract: We study, experimentally and numerically, the increase of the stimulated Brillouin scattering (SBS) threshold in dispersion-shifted fibers (DSFs) by applying three different tensile-strain distributions. The best results are obtained with a 40-step stair-ramp distribution, for which we demonstrate a 8-dB SBS threshold increase in a 580-m DSF. The Brillouin frequency is observed to shift as a function of the strain at a rate of 0.464 GHz/%. We discuss the potentials and drawbacks of this technique for application in nonlinear devices.

Electronic Band Structures of the Alkali Metals and of the Noble Metals and their α-Phase Alloys

Abstract: In the monovalent metals the electronic band structure is strongly affected by the size of the band gap E s-E p at the Brillouin zone faces, a large gap implying a large distortion of the Fermi surface. Here E s and E p are the energies of the purely s-like and p-like states on the zone faces. We have made crude estimates of E s-E p for the alkali and noble metals, in terms of the s-p excitation energy Δsp of the free atoms. These suggest a single model which correlates most of the experimental information about the band structures of these metals. In particular the Fermi surface of lithium appears to make considerable contact with the zone faces. In the α-phase alloys of the noble metals, the solute always has a larger value of Δsp than the solvent, which raises the energy E p relative to E s. The Fermi surface becomes more nearly spherical in copper alloys than in copper, since E p E s). This accounts for many Knight shift, electronic spe...

Evidence for quasiparticle decay in photoemission from underdoped cuprates

Abstract: I argue that the {open_quotes}gap{close_quotes} recently observed at the Brillouin zone face of cuprate superconductors in photoemission by Marshall {ital et al.}[Phys.Rev.Lett.{bold 76}, 4841 (1996)] and Ding {ital et al.}[Nature {bold 382}, 54 (1996)] is evidence for the decay of the injected hole into a spinon-holon pair. {copyright} {ital 1997} {ital The American Physical Society}