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Spin‐to‐charge conversion (SCC) involving topological surface states (TSS) is one of the most promising routes for highly efficient spintronic devices for terahertz (THz) emission. Here, the THz generation generally occurs mainly via SCC consisting in efficient dynamical spin injection into spin‐locked TSS. In this work, sizable THz emission from a nanometric thick topological insulator (TI)/ferromagnetic junction—SnBi2Te4/Co—specifically designed to avoid bulk band crossing with the TSS at the Fermi level, unlike its parent material Bi2Te3 is demonstrated. THz emission time domain spectroscopy (TDS) is used to indicate the TSS contribution to the SCC by investigating the TI thickness and angular dependence of the THz emission. This work illustrates THz emission TDS as a powerful tool alongside angular resolved photoemission spectroscopy (ARPES) methods to investigate the interfacial spintronic properties of TI/ferromagnet bilayers. [ABSTRACT FROM AUTHOR]

Plasma assisted atomic oxygen deposition was used to grow polycrystalline ferroelectric Hf1-xZrxO2 (x = 0.5–0.7) on technologically important (100) Germanium substrates showing sharp crystalline interfaces free of interfacial amorphous layers and strong evidence for the presence of a predominately orthorhombic phase. The electrical properties, evaluated using metal-ferroelectric-semiconductor (MFS) capacitors, show symmetric and robust ferroelectric hysteresis with weak or no wake-up effects. The MFS capacitors with x = 0.58 show very large remanent polarization up to 34.4 μC/cm2 or 30.6 μC/cm2 after correction for leakage and parasitics, combined with good endurance reaching 105 cycles at a cycling field of 2.3 MV/cm. The results show good prospects for the fabrication of Ge ferroelectric field effect transistors (FeFETs) for use in 1 T FeFET embedded nonvolatile memory cells with improved endurance. [ABSTRACT FROM AUTHOR]

We performed time- and polarization-resolved extreme ultraviolet momentum microscopy on the topological Dirac semimetal candidate 1T-ZrTe 2 . Excited state band mapping uncovers the previously inaccessible linear dispersion of the Dirac cone above the Fermi level. We study the orbital texture of bands using linear dichroism in photoelectron angular distributions. These observations provide hints about the topological character of 1T-ZrTe 2 . Time-, energy-, and momentum-resolved nonequilibrium carrier dynamics reveal that intra- and interband scattering processes play a major role in the relaxation mechanism, leading to multivalley electron-hole accumulation near the Fermi level. We also show that electrons' inverse lifetime has a linear dependence as a function of their excess energy. Our time- and polarization-resolved XUV photoemission results shed light on the excited state electronic structure of 1T-ZrTe 2 and provide valuable insights into the relatively unexplored field of quantum-state-resolved ultrafast dynamics in 3D topological Dirac semimetals.

Two-dimensional (2D) van der Waals (vdW) ferromagnetic metals Fe x GeTe 2 with x = 3-5 have raised significant interest in the scientific community. Fe 5 GeTe 2 shows prospects for spintronic applications since the Curie temperature T c has been reported near or higher than 300 K. In the present work, epitaxial Fe 5- δ GeTe 2 (FGT) heterostructures were grown by Molecular Beam Epitaxy (MBE) on insulating crystalline substrates. The FGT films were combined with Bi 2 Te 3 topological insulator (TI) aiming to investigate the possible beneficial effect of the TI on the magnetic properties of FGT. FGT/Bi 2 Te 3 films were compared to FGT capped only with AlO x to prevent oxidation. SQUID and MOKE measurements revealed that the growth of Bi 2 Te 3 TI on FGT films significantly enhances the saturation magnetization of FGT as well as the T c well above room temperature (RT) reaching record values of 570 K. First-principles calculations predict a shift of the Fermi level and an associated enhancement of the majority spin (primarily) as well as the total density of states at the Fermi level suggesting that effective doping of FGT from Bi 2 Te 3 could explain the enhancement of ferromagnetism in FGT. It is also predicted that strain induced stabilization of a high magnetic moment phase in FGT/Bi 2 Te 3 could be an alternative explanation of magnetization and T c enhancement. Ferromagnetic resonance measurements evidence an enhanced broadening in the FGT/Bi 2 Te 3 heterostructure when compared to FGT. We obtain a large spin mixing conductance of g ↑↓eff = 4.4 × 10 20 m -2 , which demonstrates the great potential of FGT/Bi 2 Te 3 systems for spin-charge conversion applications at room temperature.

Among ultrathin monoelemental two-dimensional (2D) materials, bismuthene, the single layer of heavier group-VΑ element bismuth (Bi), has been predicted to have large non trivial gap. Here, we demonstrate the growth of Bi films by molecular beam epitaxy on 2D-HfTe 2 template. At the initial stage of Bi deposition (1-2 bilayers, BL), both the pseudocubic Bi(110) and the hexagonal Bi(111) phases are formed. When reaching 3 BL Bi, a transformation to pure hexagonal Bi(111) occurs. The electronic band structure of 3 BL Bi(111) films was measured by angle-resolved photoemission spectroscopy showing very good matching with the density functional theory band structure calculations of 3 BL free standing Bi(111). The grown Bi(111) thin film was capped with a protective Al 2 O 3 layer and its stability under ambient conditions, necessary for practical applications and device fabrication, was confirmed by x-ray photoelectron spectroscopy and Raman spectroscopy., (© 2021 IOP Publishing Ltd.)

Abstract: Neutrophil to lymphocyte ratio has been examined among several studies regarding Henoch Schonlein purpura patients with gastrointestinal involvement. The current meta-analysis aims to evaluate neutrophil to lymphocyte ratio differences between Henoch Schonlein purpura patients with and without gastrointestinal manifestations.An extensive search of the available literature was done using MEDLINE (1966-2020), Clinicaltrials.gov (2008-2020), Cochrane Central Register of Controlled Trials (CENTRAL) (1999-2020) and Google Scholar (2004-2020) databases and statistical analysis was mainly conducted using RevMan 5.3 software.The current meta-analysis is based on data from six studies. Neutrophil to lymphocyte ratio was higher in Henoch Schonlein patients with gastrointestinal involvement than those without with a mean difference of 0.88 (95% confidence interval [CI]: 0.55, 1.22 [P < 10-5, I2 = 8%]). Low heterogeneity (I2) was observed between the included studies. Subgroup analysis, leave one out meta-analysis and meta-regression analysis were performed which led to the lowering of I2 to 0.The findings of our meta-analysis suggest that the neutrophil to lymphocyte ratio could serve as a marker of gastrointestinal involvement in patients with Henoch Schonlein purpura; however, most of the included studies are case-control, therefore future cohort studies should clarify the value of this marker., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by European Society for Pediatric Gastroenterology, Hepatology, and Nutrition and North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition.)

Single and few layers of the two-dimensional (2D) semimetal ZrTe 2 are grown by molecular beam epitaxy on InAs(111)/Si(111) substrates. Excellent rotational commensurability, van der Waals gap at the interface and moiré pattern are observed indicating good registry between the ZrTe 2 epilayer and the substrate through weak van der Waals forces. The electronic band structure imaged by angle resolved photoelectron spectroscopy shows that valence and conduction bands cross at the Fermi level exhibiting abrupt linear dispersions. The latter indicates massless Dirac Fermions which are maintained down to the 2D limit suggesting that single-layer ZrTe 2 could be considered as the electronic analogue of graphene.