Universal response of the type-II Weyl semimetals phase diagram

The discovery of Weyl semimetals represents a significant advance in topological band theory. They paradigmatically enlarged the classification of topological materials to gapless systems while simultaneously providing experimental evidence for the long-sought Weyl fermions. Beyond fundamental relevance, their high mobility, strong magnetoresistance, and the possible existence of even more exotic effects, such as the chiral anomaly, make Weyl semimetals a promising platform to develop radically new technology. Fully exploiting their potential requires going beyond the mere identification of materials and calls for a detailed characterization of their functional response, which is severely complicated by the coexistence of surface- and bulk-derived topologically protected quasiparticles, i.e., Fermi arcs and Weyl points, respectively. Here, we focus on the type-II Weyl semimetal class where we find a stoichiometry-dependent phase transition from a trivial to a non-trivial regime. By exploring the two extreme cases of the phase diagram, we demonstrate the existence of a universal response of both surface and bulk states to perturbations. We show that quasi-particle interference patterns originate from scattering events among surface arcs. Analysis reveals that topologically non-trivial contributions are strongly suppressed by spin texture. We also show that scattering at localized impurities generate defect-induced quasiparticles sitting close to the Weyl point energy. These give rise to strong peaks in the local density of states, which lift the Weyl node significantly altering the pristine low-energy Weyl spectrum. Visualizing the microscopic response to scattering has important consequences for understanding the unusual transport properties of this class of materials. Overall, our observations provide a unifying picture of the Weyl phase diagram

Single spin-polarised Fermi surface in SrTiO3_3 thin films

The 2D electron gas (2DEG) formed at the surface of SrTiO$_3$(001) has attracted great interest because of its fascinating physical properties and potential as a novel electronic platform, but up to now has eluded a comprehensible way to tune its properties. Using angle-resolved photoemission spectroscopy with and without spin detection we here show that the band filling can be controlled by growing thin SrTiO$_3$ films on Nb doped SrTiO$_3$(001) substrates. This results in a single spin-polarised 2D Fermi surface, which bears potential as platform for Majorana physics. Based on our results it can furthermore be concluded that the 2DEG does not extend more than 2 unit cells into the film and that its properties depend on the amount of SrO$_x$ at the surface and possibly the dielectric response of the system

Observation of Wannier-Stark localization at the surface of BaTiO3_3 films by photoemission

Observation of Bloch oscillations and Wannier-Stark localization of charge carriers is typically impossible in single-crystals, because an electric field higher than the breakdown voltage is required. In BaTiO$_3$ however, high intrinsic electric fields are present due to its ferroelectric properties. With angle-resolved photoemission we directly probe the Wannier-Stark localized surface states of the BaTiO$_3$ film-vacuum interface and show that this effect extends to thin SrTiO$_3$ overlayers. The electrons are found to be localized along the in-plane polarization direction of the BaTiO$_3$ film

Spin-resolved electronic response to the phase transition in MoTe2_2

The semimetal MoTe$_2$ is studied by spin- and angle- resolved photoemission spectroscopy to probe the detailed electronic structure underlying its broad range of response behavior. A novel spin-texture is uncovered in the bulk Fermi surface of the non-centrosymmetric structural phase that is consistent with first-principles calculations. The spin-texture is three-dimensional, both in terms of momentum dependence and spin-orientation, and is not completely suppressed above the centrosymmetry-breaking transition temperature. Two types of surface Fermi arc are found to persist well above the transition temperature. The appearance of a large Fermi arc depends strongly on thermal history, and the electron quasiparticle lifetimes are greatly enhanced in the initial cooling. The results indicate that polar instability with strong electron-lattice interactions exists near the surface when the bulk is largely in a centrosymmetric phase

Cellular Internalization of Human Calcitonin Derived Peptides in MDCK Monolayers: A Comparative Study with Tat(47-57) and Penetratin(43-58)

ISSN:0724-8741ISSN:1573-904

Spin polarization in photoemission from the cuprate superconductor Bi2Sr2CaCu2O8+delta

Photoelectrons produced from the excitation of spin-degenerate states in solids can have a sizable spin polarization, which is related to the phase of interfering channels in the photoemission matrix elements. Such spin polarization can be measured by spin-resolved photoemission spectroscopy to gain information about the transitions and the Wigner time delay of the process. Incorporating strongly correlated electron systems into this paradigm could yield a novel means of extracting phase information crucial to understanding the mechanism of their emergent behavior. In this work, we present, as a case study, experimental measurements of the cuprate superconductor Bi2Sr2CaCu2O8+delta by spin-resolved photoemission while maintaining full angular and energy resolution. A spin polarization of at least 10% is observed, which is related to the phase of the photoelectron wave function

Direct observation of the spin texture in strongly correlated SmB6 as evidence of the topological Kondo insulator

The concept of a topological Kondo insulator (TKI) has been brought forward as a new class of topological insulators in which non-trivial surface states reside in the bulk Kondo band gap at low temperature due to the strong spin-orbit coupling [1-3]. In contrast to other three-dimensional (3D) topological insulators (e.g. Bi2Se3), a TKI is truly insulating in the bulk [4]. Furthermore, strong electron correlations are present in the system, which may interact with the novel topological phase. Applying spin- and angle-resolved photoemission spectroscopy (SARPES) to the Kondo insulator SmB6, a promising TKI candidate, we reveal that the surface states of SmB6 are spin polarized, and the spin is locked to the crystal momentum. Counter-propagating states (i.e. at k and -k) have opposite spin polarizations protected by time-reversal symmetry. Together with the odd number of Fermi surfaces of surface states between the 4 time-reversal invariant momenta in the surface Brillouin zone [5], these findings prove, for the first time, that SmB6 can host non-trivial topological surface states in a full insulating gap in the bulk stemming from the Kondo effect. Hence our experimental results establish that SmB6 is the first realization of a 3D TKI. It can also serve as an ideal platform for the systematic study of the interplay between novel topological quantum states with emergent effects and competing order induced by strongly correlated electrons.Comment: 4 figure

Prospective Assessment of Sex-Related Differences in Symptom Status and Health Perception Among Patients With Atrial Fibrillation.

We prospectively assessed sex-specific differences in health perception, overall symptom status, and specific symptoms in a large cohort of patients with atrial fibrillation. We performed a prospective multicenter observational cohort study of 1553 patients with atrial fibrillation. Patients completed questionnaires about personal characteristics, comorbidities, and symptoms on a yearly basis. Mean age was 70±11 years among women and 67±12 years among men. Health perception on a visual analogue scale ranging from 0 to 100 (with higher scores indicating better health perception) was significantly lower in women than in men (70 [interquartile range: 50-80] versus 75 [interquartile range: 60-85]; javax.xml.bind.JAXBElement@29592a5d <0.0001). More women than men had any symptoms (85.0% versus 68.3%; javax.xml.bind.JAXBElement@7ac0b4e4 <0.0001), palpitations (65.2% versus 44.4%; javax.xml.bind.JAXBElement@41229466 <0.0001), dizziness (25.6% versus 13.5%; javax.xml.bind.JAXBElement@61871784 <0.0001), dyspnea (35.7% versus 21.8%; javax.xml.bind.JAXBElement@16cc22b <0.0001), and fatigue (25.3% versus 19.1%; javax.xml.bind.JAXBElement@7ef43176 =0.006). At 1-year follow-up, symptoms decreased in both sexes but remained more frequent in women (49.1% versus 32.6%, javax.xml.bind.JAXBElement@2b200b6a <0.0001). In multivariable adjusted longitudinal regression models, female sex remained an independent predictor for lower health perception (ß=-4.8; 95% CI, -6.5 to -3.1; javax.xml.bind.JAXBElement@72c212bd <0.0001), any symptoms (odds ratio [OR]: 2.6; 95% CI, 2.1-3.4; javax.xml.bind.JAXBElement@15d8fb54 <0.0001), palpitations (OR: 2.6; 95% CI, 2.1-3.2; javax.xml.bind.JAXBElement@4af80718 <0.0001), dizziness (OR: 2.9; 95% CI, 2.1-3.9; javax.xml.bind.JAXBElement@61282e76 <0.0001), dyspnea (OR: 2.1; 95% CI, 1.6-2.8; javax.xml.bind.JAXBElement@31d9f14 <0.0001), fatigue (OR: 1.6; 95% CI, 1.2-2.2; javax.xml.bind.JAXBElement@51cdd678 =0.0008), and chest pain (OR: 1.8; 95% CI, 1.3-2.6; javax.xml.bind.JAXBElement@5b87db9e =0.001). Women with atrial fibrillation have a substantially higher symptom burden and lower health perception than men. These relationships persisted after multivariable adjustment and during prospective follow-up

Tectonic Controls on Gas Hydrate Distribution off SW Taiwan

The northern part of the South China Sea is characterized by widespread occurrence of bottom simulating reflectors (BSR) indicating the presence of marine gas hydrate. Because the area covers both a tectonically inactive passive margin and the termination of a subduction zone, the influence of tectonism on the dynamics of gas hydrate systems can be studied in this region. Geophysical data show that there are multiple thrust faults on the active margin while much fewer and smaller faults exist in the passive margin. This tectonic difference matches with a difference in the geophysical characteristics of the gas hydrate systems. High hydrate saturation derived from ocean bottom seismometer data and controlled source electromagnetic data and conspicuous high‐amplitude reflections in P‐Cable 3D seismic data above the BSR are found in the anticlinal ridges of the active margin. In contrast all geophysical evidence for the passive margin points to normal to low hydrate saturations. Geochemical analyses of gas samples collected at seep sites on the active margin show methane with heavy δ13C isotope composition, while gas collected at the passive margin shows light carbon isotope composition. Thus, we interpret the passive margin as a typical gas hydrate province fuelled by biogenic production of methane and the active margin gas hydrate system as a system that is fuelled not only by biogenic gas production but also by additional advection of thermogenic methane from the subduction system