Electron-driven processes in enantiomeric forms of glutamic acid initiated by low-energy resonance electron attachment.

Low-energy (0-14 eV) resonance electron interaction and fragment species produced by dissociative electron attachment (DEA) for enantiomeric forms of glutamic acid (Glu) are studied under gas-phase conditions by means of DEA spectroscopy and density functional theory calculations. Contrary to a series of amino acids studied earlier employing the DEA technique, the most abundant species are not associated with the elimination of a hydrogen atom from the parent molecular negative ion. Besides this less intense closed-shell [Glu - H]- fragment, only two mass-selected negative ions, [Glu - 19]- and [Glu - 76]-, are detected within the same electron energy region, with the yield maximum observed at around 0.

Evolution of MnGeBiTe Electronic Structure under Variation of Ge Content.

One of the approaches to manipulate MnBi2Te4 properties is the magnetic dilution, which inevitably affects the interplay of magnetism and band topology in the system. In this work, we carried out angle-resolved photoemission spectroscopy (ARPES) measurements and density functional theory (DFT) calculations for analysing changes in the electronic structure of Mn1-xGexBi2Te4 that occur under parameter x variation. We consider two ways of Mn/Ge substitution: (i) bulk doping of the whole system; (ii) surface doping of the first septuple layer.

Semiconducting Electronic Structure of the Ferromagnetic Spinel HgCr_{2}Se_{4} Revealed by Soft-X-Ray Angle-Resolved Photoemission Spectroscopy.

We study the electronic structure of the ferromagnetic spinel HgCr_{2}Se_{4} by soft-x-ray angle-resolved photoemission spectroscopy (SX-ARPES) and first-principles calculations. While a theoretical study has predicted that this material is a magnetic Weyl semimetal, SX-ARPES measurements give direct evidence for a semiconducting state in the ferromagnetic phase. Band calculations based on the density functional theory with hybrid functionals reproduce the experimentally determined band gap value, and the calculated band dispersion matches well with ARPES experiments.

Vacuum Spin LED: First Step towards Vacuum Semiconductor Spintronics.

Improving the efficiency of spin generation, injection, and detection remains a key challenge for semiconductor spintronics. Electrical injection and optical orientation are two methods of creating spin polarization in semiconductors, which traditionally require specially tailored p-n junctions, tunnel or Schottky barriers. Alternatively, we introduce here a novel concept for spin-polarized electron emission/injection combining the optocoupler principle based on vacuum spin-polarized light-emitting diode (spin VLED) making it possible to measure the free electron beam polarization injected into the III-V heterostructure with quantum wells (QWs) based on the detection of polarized cathodoluminescence (CL).

Correction: Depth-resolved oxidational studies of Be/Al periodic multilayers investigated by X-ray photoelectron spectroscopy.

Correction for 'Depth-resolved oxidational studies of Be/Al periodic multilayers investigated by X-ray photoelectron spectroscopy' by Niranjan Kumar , , 2023, , 1205-1213, https://doi.org/10.1039/D2CP04778K.

Depth-resolved oxidational studies of Be/Al periodic multilayers investigated by X-ray photoelectron spectroscopy.

The quantification of surface and subsurface oxidation of Be/Al periodic multilayer mirrors due to exposure in the ambient atmosphere was investigated by depth-resolved X-ray photoelectron spectroscopy. The contribution of oxidation was lower for the thicker layer of Al in the periodic structures since the surface was less chemically reactive for the oxidation. This was investigated by finding the depth-resolved slope of the intensity ratio of metal/oxides (Be/BeO and Al/AlO) by analyzing the chemical shift of Al 1s and Be 1s photoelectrons.

Ferromagnetic Layers in a Topological Insulator (Bi,Sb)Te Crystal Doped with Mn.

Magnetic topological insulators (MTIs) have recently become a subject of poignant interest; among them, Z topological insulators with magnetic moment ordering caused by embedded magnetic atoms attract special attention. In such systems, the case of magnetic anisotropy perpendicular to the surface that holds a topologically nontrivial surface state is the most intriguing one. Such materials demonstrate the quantum anomalous Hall effect, which manifests itself as chiral edge conduction channels that can be manipulated by switching the polarization of magnetic domains.

Electronic Structure of Pb Adsorbed Surfaces of Intrinsic Magnetic Topological Insulators.

Recently discovered intrinsic magnetic topological insulators (IMTIs) constitute a unique class of quantum materials that combine magnetism and nontrivial topology. One of the most promising applications of these materials is Majorana fermion creation; Majorana fermions are expected to arise when a superconductor is in contact with the surface of an IMTI. Here we study the adsorption of Pb ultrathin films on top of IMTIs of various stoichiometries.

A volume plasmon blueshift in thin silicon films embedded within Be/Si periodic multilayer mirrors.

Microstructural properties of the beryllium (Be) and silicon (Si) in periodic multilayer mirrors Be/Si with the variation of film thickness were comprehensively determined by Raman scattering. For the thinner films, the structure of Be evolved in the amorphous phase, and it was transformed into the polycrystalline phase for thicker films. The Si films in the periodic structure were condensed into the amorphous phase.

A new imaging concept in spin polarimetry based on the spin-filter effect.

The concept of an imaging-type 3D spin detector, based on the combination of spin-exchange interactions in the ferromagnetic (FM) film and spin selectivity of the electron-photon conversion effect in a semiconductor heterostructure, is proposed and demonstrated on a model system. This novel multichannel concept is based on the idea of direct transfer of a 2D spin-polarized electron distribution to image cathodoluminescence (CL). The detector is a hybrid structure consisting of a thin magnetic layer deposited on a semiconductor structure allowing measurement of the spatial and polarization-dependent CL intensity from injected spin-polarized free electrons.

Correlation of elastic and optoelectronic properties near structural phase transition in organic-inorganic lead iodide perovskite single crystals.

The experimental evidence of the influence of the structural phase transition on the elastic and optoelectronic properties of CHNHPbIsingle crystals has been reported. A peak in the attenuation for longitudinal and shear ultrasonic waves and a step-like anomaly in their velocity have been found near the structural the orthorhombic-to-tetragonal phase transition (160 K). The narrow hysteresis observed in the temperature dependences of the elastic properties confirms that this is the first-order phase transition.

Topologically Nontrivial Phase-Change Compound GeSbTe.

Chalcogenide phase-change materials show strikingly contrasting optical and electrical properties, which has led to their extensive implementation in various memory devices. By performing spin-, time-, and angle-resolved photoemission spectroscopy combined with the first-principles calculation, we report the experimental results that the crystalline phase of GeSbTe is topologically nontrivial in the vicinity of the Dirac semimetal phase. The resulting linearly dispersive bulk Dirac-like bands that cross the Fermi level and are thus responsible for conductivity in the stable crystalline phase of GeSbTe can be viewed as a 3D analogue of graphene.

Electrically Controlled Spin Injection from Giant Rashba Spin-Orbit Conductor BiTeBr.

Ferromagnetic materials are the widely used source of spin-polarized electrons in spintronic devices, which are controlled by external magnetic fields or spin-transfer torque methods. However, with increasing demand for smaller and faster spintronic components utilization of spin-orbit phenomena provides promising alternatives. New materials with unique spin textures are highly desirable since all-electric creation and control of spin polarization is expected where the strength, as well as an arbitrary orientation of the polarization, can be defined without the use of a magnetic field.

Shubnikov-de Haas oscillations in p and n-type topological insulator (Bi Sb )Te.

We show Shubnikov-de Haas (SdH) oscillations in topological insulator (Bi Sb )Te flakes whose carrier types are p-type (x  =  0.29, 0.34) and n-type (x  =  0.

Single Electron Gating of Topological Insulators.

The effective gating of topological insulators is demonstrated, through the coupling of molecules to their surface. By using electric fields, they allow for dynamic control of the interface charge state by adding or removing single electrons. This process creates a robust transconductance bistability resembling a single-electron transistor.

Dual nature of magnetic dopants and competing trends in topological insulators.

Topological insulators interacting with magnetic impurities have been reported to host several unconventional effects. These phenomena are described within the framework of gapping Dirac quasiparticles due to broken time-reversal symmetry. However, the overwhelming majority of studies demonstrate the presence of a finite density of states near the Dirac point even once topological insulators become magnetic.

Spin-texture inversion in the giant Rashba semiconductor BiTeI.

Semiconductors with strong spin-orbit interaction as the underlying mechanism for the generation of spin-polarized electrons are showing potential for applications in spintronic devices. Unveiling the full spin texture in momentum space for such materials and its relation to the microscopic structure of the electronic wave functions is experimentally challenging and yet essential for exploiting spin-orbit effects for spin manipulation. Here we employ a state-of-the-art photoelectron momentum microscope with a multichannel spin filter to directly image the spin texture of the layered polar semiconductor BiTeI within the full two-dimensional momentum plane.

Experimental Realization of a Topological p-n Junction by Intrinsic Defect Grading.

A Bi2Te3 single crystal is grown with the modified Bridgman technique. The crystal has a nominal composition with a Te content of 61 mol% resulting in the existence of two distinct regions, p- and n-doped, respectively; color-coded tunneling spectra are taken over 60 nm at the transition region.

Plasma-Wave Terahertz Detection Mediated by Topological Insulators Surface States.

Topological insulators (TIs) represent a novel quantum state of matter, characterized by edge or surface-states, showing up on the topological character of the bulk wave functions. Allowing electrons to move along their surface, but not through their inside, they emerged as an intriguing material platform for the exploration of exotic physical phenomena, somehow resembling the graphene Dirac-cone physics, as well as for exciting applications in optoelectronics, spintronics, nanoscience, low-power electronics, and quantum computing. Investigation of topological surface states (TSS) is conventionally hindered by the fact that in most of experimental conditions the TSS properties are mixed up with those of bulk-states.

Signatures of Dirac fermion-mediated magnetic order.

The spin-momentum locking of topological states offers an ideal platform to explore novel magnetoelectric effects. These intimately depend on the ability to manipulate the spin texture in a controlled way. Here we combine scanning tunnelling microscopy with single-atom deposition to map the evolution of topological states under the influence of different magnetic perturbations.