Self-Intercalation as Origin of High-Temperature Ferromagnetism in Epitaxially Grown Fe_{5}GeTe_{2} Thin Films.

The role of self-intercalation in 2D van der Waals materials is key to the understanding of many of their properties. Here we show that the magnetic ordering temperature of thin films of the 2D ferromagnet Fe_{5}GeTe_{2} is substantially increased by self-intercalated Fe that resides in the van der Waals gaps. The epitaxial films were prepared by molecular beam epitaxy and their magnetic properties explored by element-specific x-ray magnetic circular dichroism that showed ferromagnetic ordering up to 375 K.

Atomic Displacements Enabling the Observation of the Anomalous Hall Effect in a Non-Collinear Antiferromagnet.

Antiferromagnets with non-collinear spin structures display various properties that make them attractive for spintronic devices. Some of the most interesting examples are an anomalous Hall effect despite negligible magnetization and a spin Hall effect with unusual spin polarization directions. However, these effects can only be observed when the sample is set predominantly into a single antiferromagnetic domain state.

Observation of Néel-type skyrmions in acentric self-intercalated CrTe.

Transition-metal dichalcogenides intercalated with 3d-transition metals within the van der Waals (vdW) gaps have been the focus of intense investigations owing to their fascinating structural and magnetic properties. At certain concentrations the intercalated atoms form ordered superstructures that exhibit ferromagnetic or anti-ferromagnetic ordering. Here we show that the self-intercalated compound CrTe with δ ≈ 0.

Fermi surface chirality induced in a TaSe monosheet formed by a Ta/BiSe interface reaction.

Spin-momentum locking in topological insulators and materials with Rashba-type interactions is an extremely attractive feature for novel spintronic devices and is therefore under intense investigation. Significant efforts are underway to identify new material systems with spin-momentum locking, but also to create heterostructures with new spintronic functionalities. In the present study we address both subjects and investigate a van der Waals-type heterostructure consisting of the topological insulator BiSe and a single Se-Ta-Se triple-layer (TL) of H-type TaSe grown by a method which exploits an interface reaction between the adsorbed metal and selenium.

Control of Oxygen Vacancy Ordering in Brownmillerite Thin Films via Ionic Liquid Gating.

Oxygen defects and their atomic arrangements play a significant role in the physical properties of many transition metal oxides. The exemplary perovskite SrCoO (SCO) is metallic and ferromagnetic. However, its daughter phase, the brownmillerite SrCoO (SCO), is insulating and an antiferromagnet.

Magnetic Skyrmions in a Thickness Tunable 2D Ferromagnet from a Defect Driven Dzyaloshinskii-Moriya Interaction.

There is considerable interest in van der Waals (vdW) materials as potential hosts for chiral skyrmionic spin textures. Of particular interest is the ferromagnetic, metallic compound Fe GeTe (FGT), which has a comparatively high Curie temperature (150-220 K). Several recent studies have reported the observation of chiral Néel skyrmions in this compound, which is inconsistent with its presumed centrosymmetric structure.

Nanoscale Noncollinear Spin Textures in Thin Films of a D Heusler Compound.

Magnetic nano-objects, namely antiskyrmions and Bloch skyrmions, have been found to coexist in single-crystalline lamellae formed from bulk crystals of inverse tetragonal Heusler compounds with D symmetry. Here evidence is shown for magnetic nano-objects in epitaxial thin films of Mn RhSn formed by magnetron sputtering. These nano-objects exhibit a wide range of sizes with stability with respect to magnetic field and temperature that is similar to single-crystalline lamellae.

Scaling trends of bird's alular feathers in connection to leading-edge vortex flow over hand-wing.

An aerodynamic structure ubiquitous in Aves is the alula; a small collection of feathers muscularized near the wrist joint. New research into the aerodynamics of this structure suggests that its primary function is to induce leading-edge vortex (LEV) flow over bird's outer hand-wing to enhance wing lift when manuevering at slow speeds. Here, we explore scaling trends of the alula's spanwise position and its connection to this function.

Transient pressure modeling in jetting animals.

There are many marine animals that employ a form of jet propulsion to move through the water, often creating the jets by expanding and collapsing internal fluid cavities. Due to the unsteady nature of this form of locomotion and complex body/nozzle geometries, standard modeling techniques prove insufficient at capturing internal pressure dynamics, and hence swimming forces. This issue has been resolved with a novel technique for predicting the pressure inside deformable jet producing cavities (M.

A three-dimensional momentum-space calculation of three-body bound state in a relativistic Faddeev scheme.

In this paper, we study the relativistic effects in a three-body bound state. For this purpose, the relativistic form of the Faddeev equations is solved in momentum space as a function of the Jacobi momentum vectors without using a partial wave decomposition. The inputs for the three-dimensional Faddeev integral equation are the off-shell boost two-body t-matrices, which are calculated directly from the boost two-body interactions by solving the Lippmann-Schwinger equation.

A bismuth triiodide monosheet on BiSe(0001).

A stable BiI monosheet has been grown for the first time on the (0001) surface of the topological insulator BiSe as confirmed by scanning tunnelling microscopy, surface X-ray diffraction, and X-ray photoemision spectroscopy. BiI is deposited by molecular beam epitaxy from the crystalline BiTeI precursor that undergoes decomposition sublimation. The key fragment of the bulk BiI structure, [Formula: see text][I-Bi-I] layer of edge-sharing BiI octahedra, is preserved in the ultra-thin film limit, but exhibits large atomic relaxations.

A Soft End Effector Inspired by Cephalopod Suckers and Augmented by a Dielectric Elastomer Actuator.

This article describes a soft suction cup end effector with squid-inspired suction generation and an octopus-inspired cup design that uses a dielectric elastomer actuator (DEA) to generate suction for adhesion. The fabrication process for the end effector is described in detail, and a mechanical model for generated pressure differential as a function of voltage is presented. When actuated, the DEA exerts an electrostatic stress on the walls of the end effector, resulting in pressure reduction in its water-filled cavity.

A Comparative Evaluation of ELISA, PCR, and Serum Agglutination Tests For Diagnosis of Brucella Using Human Serum.

Background & Objective: Since the symptoms of Brucellosis are often atypical and nonspecific, using clinical signs alone to diagnose brucellosis is not advised; therefore, the diagnosis relies predominantly on laboratory testing. Currently, molecular, serological, and microbiological methods are used for diagnosis of this disease. In this study we examined ELISA, PCR and serum agglutination (SAT) methods on human patient serum samples.

A vortex model for forces and moments on low-aspect-ratio wings in side-slip with experimental validation.

This paper studies low-aspect-ratio ([Formula: see text]) rectangular wings at high incidence and in side-slip. The main objective is to incorporate the effects of high angle of attack and side-slip into a simplified vortex model for the forces and moments. Experiments are also performed and are used to validate assumptions made in the model.

Reversible Formation of 2D Electron Gas at the LaFeO /SrTiO Interface via Control of Oxygen Vacancies.

A conducting 2D electron gas (2DEG) is formed at the interface between epitaxial LaFeO layers >3 unit cells thick and the surface of SrTiO single crystals. The 2DEG is exquisitely sensitive to cation intermixing and oxygen nonstoichiometry. It is shown that the latter thus allows the controllable formation of the 2DEG via ionic liquid gating, thereby forming a nonvolatile switch.

Unified slip boundary condition for fluid flows.

Determining the correct matching boundary condition is fundamental to our understanding of several everyday problems. Despite over a century of scientific work, existing velocity boundary conditions are unable to consistently explain and capture the complete physics associated with certain common but complex problems, such as moving contact lines and corner flows. The widely used Maxwell and Navier slip boundary conditions make an implicit assumption that velocity varies only in the wall normal direction.

Observation and Structure Determination of an Oxide Quasicrystal Approximant.

We report on the first observation of an approximant structure to the recently discovered two-dimensional oxide quasicrystal. Using scanning tunneling microscopy, low-energy electron diffraction, and surface x-ray diffraction in combination with ab initio calculations, the atomic structure and the bonding scheme are determined. The oxide approximant follows a 3^{2}.

Design considerations for an underwater soft-robot inspired from marine invertebrates.

This article serves as an overview of the unique challenges and opportunities made possible by a soft, jellyfish inspired, underwater robot. We include a description of internal pressure modeling as it relates to propulsive performance, leading to a desired energy-minimizing volume flux program. Strategies for determining optimal actuator placement derived from biological body motions are presented.

Identifying and modeling motion primitives for the hydromedusae Sarsia tubulosa and Aequorea victoria.

The movements of organisms can be thought of as aggregations of motion primitives: motion segments containing one or more significant actions. Here, we present a means to identify and characterize motion primitives from recorded movement data. We address these problems by assuming that the motion sequences can be characterized as a series of dynamical-system-based pattern generators.

Tuning the Dirac point position in Bi(2)Se(3)(0001) via surface carbon doping.

Angular resolved photoemission spectroscopy in combination with ab initio calculations show that trace amounts of carbon doping of the Bi_{2}Se_{3} surface allows the controlled shift of the Dirac point within the bulk band gap. In contrast to expectation, no Rashba-split two-dimensional electron gas states appear. This unique electronic modification is related to surface structural modification characterized by an expansion of the top Se-Bi spacing of ≈11% as evidenced by surface x-ray diffraction.

Tuning the structure of ultrathin BaTiO3 films on Me(001) (Me=Fe, Pd, Pt) surfaces.

Using surface x-ray diffraction in combination with ab initio calculations, we demonstrate that the atomic structure of ultrathin BaTiO3 (BTO) films grown on Me(001) surfaces (Me=Fe, Pd, Pt) depends on subtle modifications of the interface chemical composition. A complete reversal of the surface termination from a BaO- [BTO on Fe(001)] to a TiO2-terminated film [BTO on Pt(001)] is observed which goes in parallel with the adsorption of submonolayer amounts of oxygen at metal hollow sites of the interface. Our results may suggest a new route to an overall control of both the surface and the interface geometry in BaTiO3/metal contacts.

Comparision of two different preparation protocol of Ni-Ti Rotary PathFile-ProTaper instruments in simulated s-shaped canals.

Introduction: The aim of this study is to compare the root canal transportation with the PathFile-ProTaper recommended protocol, PathFile-ProTaper modified protocol and stainless steel K-flexofiles.

Methods: Forty-five ISO 15, 0.02 taper S-shaped Endo Training Blocks were divided randomly into three groups of 15 each and prepared as follows: PathFile-Protaper recommended protocol, Pathfile-Protaper modified protocol and manual preparation with K-Flexofiles.

Misfit-induced modification of structure and magnetism in O/Fe(001)-p(1×1).

The geometry of oxygen atoms in hollow sites of Fe nanoislands (⊘≈1-2  nm) on Fe(001) is modified by mesoscopic misfit-induced relaxations of the island atoms. Surface x-ray diffraction, scanning tunneling microscopy, and ab initio calculations indicate a 0.3 Å increased adsorption height [0.

BaTiO3(001)-(2×1): surface structure and spin density.

Using surface x-ray diffraction and ab initio calculations we present a model of the BaTiO3(001)-(2×1) surface structure, which has not been considered so far. While the crystal is terminated by two TiO2 layers similarly to SrTiO3(001)-(2×1), we find that one out of two surface layer Ti-atoms resides in a tetragonal pyramidal oxygen environment. This peculiar geometry leads to a metallic and magnetic surface involving local magnetic moments up to 2μ(B) in magnitude located at surface Ti and O atoms.

A model of the lateral line of fish for vortex sensing.

In this paper, the lateral line trunk canal (LLTC) of a fish is modeled to investigate how it is affected by an external flow field. Potential flow theory is adopted to model the flow field around a fish's body in the presence of a Karman vortex street. Karman and reverse Karman streets represent the flow patterns behind a bluff body and a traveling fish, respectively.