Unveiling the stacking-dependent electronic properties of 2D ultrathin rare-earth metalloxenes family LnX2_2 (Ln = Eu, Gd, Dy; X = Ge, Si)

The studies of electronic effects in reduced dimensionality have become a frontier in nanoscience due to exotic and highly tunable character of quantum phenomena. Recently, a new class of 2D ultrathin Ln$X_2$ metalloxenes composed of a triangular lattice of lanthanide ions (Ln) coupled with 2D-Xenes of silicene or germanene ($X_2$) was introduced and studied with a particular focus on magnetic and transport properties. However, the electronic properties of metalloxenes and their effective functionalization remain mainly unexplored. Here, using a number of experimental and theoretical techniques, we trace the evolution of electronic properties and magnetic ground state of metalloxenes triggered by external perturbations. We demonstrate that the band structure of Ln$X_2$ films can be uniquely modified by controlling the Xenes stacking, thickness, varying the rare-earth and host elements, and applying an external electric field. Our findings suggest new pathways to manipulate the electronic properties of 2D rare-earth magnets that can be adjusted for spintronics applications.Comment: 7 pages, 3 figure

Single layer nickel disilicide on surface and as embedded layer

Single monolayers of various materials (e.g. graphene, silicene, bismuthene, plumbene, etc) have recently become fascinating and promising objects in modern condensed-matter physics and nanotechnology. However, growing a monolayer of non-layered material is still challenging. In the present report, it will be shown that single monolayer NiSi2 can be fabricated at Si(111) surface stabilized by either Tl, Pb or In monolayers. Nickel atoms were found to intercalate the stabilizing metal layers upon deposition and to reside in the interstitial sites inside the first silicon bilayer of bulk-like-terminated Si(111)1×1 surface. The interstitial positions almost coincide with the bulk NiSi2 atomic positions thus forming NiSi2 single layer. Atomic and electronic structure of formed systems is described in detail by means of a set of experimental techniques, including low-energy electron diffraction, scanning tunneling microscopy, angle-resolved photoemission spectroscopy and also first-principles density-functional-theory calculations. Quality of formed single monolayer NiSi2 was additionally confirmed by in situ four-probe transport measurements that show that single monolayer NiSi2 preserves a metallic-type conductivity down to 2.0 K. Moreover it was found that delta-type structure with atomic sheet of NiSi2 silicide embedded into a crystalline Si matrix can be fabricated using room-temperature overgrowth of a Si film onto the Tl stabilized NiSi2 surface layer. Confinement of the NiSi2 layer to a single atomic plane has been directly confirmed by high-resolution transmission electron microscopy

Synthesis of two-dimensional TlxBi1-x compounds and Archimedean encoding of their atomic structure

Crystalline atomic layers on solid surfaces are composed of a single building block, unit cell, that is copied and stacked together to form the entire two-dimensional crystal structure. However, it appears that this is not an unique possibility. We report here on synthesis and characterization of the one-atomic-layer-thick TlxBi1−x compounds which display quite a different arrangement. It represents a quasi-periodic tiling structures that are built by a set of tiling elements as building blocks. Though the layer is lacking strict periodicity, it shows up as an ideally-packed tiling of basic elements without any skips or halting. The two-dimensional TlxBi1−x compounds were formed by depositing Bi onto the Tl-covered Si(111) surface where Bi atoms substitute appropriate amount of Tl atoms. Atomic structure of each tiling element as well as arrangement of TlxBi1−x compounds were established in a detail. Electronic properties and spin texture of the selected compounds having periodic structures were characterized. The shown example demonstrates possibility for the formation of the exotic low-dimensional materials via unusual growth mechanisms

Metal hydride hydrogen storage and compression systems for energy storage technologies

Along with a brief overview of literature data on energy storage technologies utilising hydrogen and metal hydrides, this article presents results of the related R&D activities carried out by the authors. The focus is put on proper selection of metal hydride materials on the basis of AB5- and AB2-type intermetallic compounds for hydrogen storage and compression applications, based on the analysis of PCT properties of the materials in systems with H2 gas. The article also presents features of integrated energy storage systems utilising metal hydride hydrogen storage and compression, as well as their metal hydride based components developed at IPCP and HySA Systems

Challenging diagnosis of amebiasis in a non-endemic region: a clinical case

In Russia, amebiasis is sporadically registered mainly in the southern regions. An endemic area is the Republic of Dagestan. We describe a clinical case, which illustrates challenges in the diagnosis of amebial colitis related to low awareness of physicians of parasitic diseases in non-endemic regions. A 38-year old female patient living in Moscow was initially misdiagnosed with Crohn's disease. Erosive and ulcerative colonic lesions found at colonoscopy were interpreted by a gastroenterologist as symptoms of an inflammatory bowel disease. No differential diagnosis with infections and parasitic diseases was performed. Long (2 years) persistence of symptoms despite treatment with 5-aminosalicylic agents for suspected Crohn's disease, absence of any significant laboratory abnormalities and no history of travelling to Asian countries were the reason for subsequent additional diagnostic work-up. After the patient was finally diagnosed with intestinal amebiasis, she was treated with metronidazole with some positive effect of decreased abdominal bloating and bowel growling. At the control colonoscopy, there was a positive trend seen in colonic mucosa, with healing of ulcers without any scarring. No protozoan cysts were any more found in her feces. According to the recommendations, the patient is regularly seen by a specialist in infectious diseases and a gastroenterologist. Expansion of amebiasis outside endemic regions points to the necessity to perform a wider diagnostic work-up in cases of mucosal lesions found at colonoscopy

Application of finite element analysis in the development of the pedal assembly of the Formula Student racing car

The study is focused on presenting an assessment of additive manufacturing usage in modern technological processes, including the manufacturing of parts of the racing car participating in Formula Student project. It shows the necessity of simulating physical processes during the design stage using the finite element analysis. The issues of calculating the strength of pedals of various functional purposes are considered. The boundary conditions imposed on the accelerator pedal are presented. It was found that loads applied with an offset to the edge of the support platform cause higher stresses in the item. The distribution patterns of the safety factor of an accelerator pedal created by additive method from materials: acrylonitrile butadiene styrene, polyamide Nylon 6/6 and polyamide Nylon 6/6 reinforced with fiberglass are presented. The results of modeling the rigidity of the pedal structure and the maximum stresses arising in it under load are indicated. The results of simulation of the prefabricated structure of the accelerator pedal with an aluminum alloy lever with a pedal plate obtained by additive manufacturing are shown

Two-dimensional in-Sb compound on silicon as a quantum spin hall insulator

Two-dimensional (2D) topological insulator is a promising quantum phase for achieving dissipationless transport due to the robustness of the gapless edge states resided in the insulating gap providing realization of the quantum spin Hall effect. Searching for two-dimensional realistic materials that are able to provide the quantum spin Hall effect and possessing the feasibility of their experimental preparation is a growing field. Here we report on the twodimensional (In, Sb)2 3 ×2 3 compound synthesized on Si(111) substrate and its comprehensive experimental and theoretical investigations based on an atomic-scale characterization by using scanning tunneling microscopy and angle-resolved photoelectron spectroscopy as well as ab initio density functional theory calculations identifying the synthesized 2D compound as a suitable system for realization of the quantum spin Hall effect without additional functionalization like chemical adsorption, applying strain, or gating

Electronic properties of the two-dimensional (Tl, Rb)/Si(1 1 1)√3x√3 compound having a honeycomb-like structure

Heavy metal layers having a honeycomb structure on the Si(1 1 1) surface were theoretically predicted to show prospects for possessing properties of the quantum spin Hall (QSH) insulators. The (Tl, Rb)/Si(1 1 1) atomic-layer compound synthesized in the present work is the first real system of such type, where atoms of heavy metal Tl are arranged into the honeycomb structure stabilized by Rb atoms occupying the centers of the honeycomb units. Electronic properties of the (Tl, Rb)/Si(1 1 1) compound has been fully characterized experimentally and theoretically and compared with those of the hypothetical (Tl, H)/Si(1 1 1) prototype system. It is concluded that the QSH-insulator properties of the Tl-honeycomb layers on Si(1 1 1) surface are dictated by the stable adsorption sites occupied by Tl atoms which, in turn, are controlled by the atom species centering the Tl honeycombs. As a result, the real (Tl, Rb)/Si(1 1 1) compound where Tl atoms occupy the T4 sites does not possess QSH-insulator properties in contrast to the hypothetical (Tl, H)/Si(1 1 1) system where Tl atoms reside in the T1 (on-top) sites and it shows up as a QSH material

Electronic properties of the two-dimensional (Tl, Rb)/Si(1 1 1)√3x√3 compound having a honeycomb-like structure

Heavy metal layers having a honeycomb structure on the Si(1 1 1) surface were theoretically predicted to show prospects for possessing properties of the quantum spin Hall (QSH) insulators. The (Tl, Rb)/Si(1 1 1) atomic-layer compound synthesized in the present work is the first real system of such type, where atoms of heavy metal Tl are arranged into the honeycomb structure stabilized by Rb atoms occupying the centers of the honeycomb units. Electronic properties of the (Tl, Rb)/Si(1 1 1) compound has been fully characterized experimentally and theoretically and compared with those of the hypothetical (Tl, H)/Si(1 1 1) prototype system. It is concluded that the QSH-insulator properties of the Tl-honeycomb layers on Si(1 1 1) surface are dictated by the stable adsorption sites occupied by Tl atoms which, in turn, are controlled by the atom species centering the Tl honeycombs. As a result, the real (Tl, Rb)/Si(1 1 1) compound where Tl atoms occupy the T4 sites does not possess QSH-insulator properties in contrast to the hypothetical (Tl, H)/Si(1 1 1) system where Tl atoms reside in the T1 (on-top) sites and it shows up as a QSH material

(Tl, Au)/Si(1 1 1)√7×√7 2D compound: an ordered array of identical Au clusters embedded in Tl matrix

Formation of the highly-ordered √7×√7-periodicity 2D compound has been detected in the (Tl, Au)/Si(111) system as a result of Au deposition onto the Tl/Si(111) surface and its composition, structure and electronic properties have been characterized using scanning tunneling microscopy and angle-resolved photoelectron spectroscopy observations and density-functional-theory calculations. On the basis of these data, the structural model of the Tl-Au compound has been proposed, which adopts 12 Tl atoms and 10 Au atoms (in total, 22 atoms) per √7×√7 unit cell, i.e. ∼1.71 ML of Tl and ∼1.43 ML of Au (in total, ∼3.14 ML). Qualitatively, the model can be visualized as consisting of truncated-pyramid-like Au clusters with a Tl atom on top, while the other Tl atoms form a double layer around the Au clusters. The (Tl, Au)/Si(111)√7×√7 compound has been found to exhibit pronounced metallic properties at least down to temperatures as low as ∼25 K, which makes it a promising object for studying electrical transport phenomena in the 2D metallic systems