Double Fe-impurity charge state in the topological insulator Bi2_2Se3_3

The influence of individual impurities of Fe on the electronic properties of topological insulator Bi$_2$Se$_3$ is studied by Scanning Tunneling Microscopy. The microscope tip is used in order to remotely charge/discharge Fe impurities. The charging process is shown to depend on the impurity location in the crystallographic unit cell, on the presence of other Fe impurities in the close vicinity, as well as on the overall doping level of the crystal. We present a qualitative explanation of the observed phenomena in terms of tip-induced local band bending. Our observations evidence that the specific impurity neighborhood and the position of the Fermi energy with respect to the Dirac point and bulk bands have both to be taken into account when considering the electron scattering on the disorder in topological insulators.Comment: 10 pages, accepted for publication in Applied Physics Letters, minor bugs were correcte

Non-biological complex drugs and their analogues in the pathogenetic therapy of multiple sclerosis: Issues of efficacy and safety in clinical use

The paper generalizes the experience with one of the main original drugs for the treatment of multiple sclerosis (MS) – glatiramer acetate (GA, Copaxone®, Teva) in large Russian MS centers. The performed analysis of clinical trials suggests the high efficacy and favorable safety profile of the drug. The fact that patents for a number of effective and widely used original drugs, including those for agents from a group of immunomodulators, used to treat MS expire is one of the features of the current development of medicine. Due to the fact that most of them belong to interferons-β, i.e. biologicals, or structurally close to nonbiological complex drugs, the authors discuss the need to conduct comparative clinical trials of the original drug and follow-on glatiramoids with measured endpoints that can be used to establish their efficacy, safety, and evidence for therapeutic equivalence in order to examine their potential interchangeability

Fourier transform spectroscopy and coupled-channel deperturbation treatment of the A1Sigma+ ~ b3Pi complex of KCs molecule

The laser induced fluorescence (LIF) spectra A1Sigma ~ b3Pi --> X1Sigma+ of KCs dimer were recorded in near infrared region by Fourier Transform Spectrometer with a resolution of 0.03 cm-1. Overall more than 200 LIF spectra were rotationally assigned to 39K133Cs and 41K133Cs isotopomers yielding with the uncertainty of 0.003-0.01 cm-1 more than 3400 rovibronic term values of the strongly mixed singlet A1Sigma+ and triplet b3Pi states. Experimental data massive starts from the lowest vibrational level v_A=0 of the singlet and nonuniformly cover the energy range from 10040 to 13250 cm-1 with rotational quantum numbers J from 7 to 225. Besides of the dominating regular A1Sigma+ ~ b3P Omega=0 interactions the weak and local heterogenous A1S+ ~ b3P Omega=1 perturbations have been discovered and analyzed. Coupled-channel deperturbation analysis of the experimental 39K133Cs e-parity termvalues of the A1S+ ~ b3P complex was accomplished in the framework of the phenomenological 4 x 4 Hamiltonian accounting implicitly for regular interactions with the remote states manifold. The resulting diabatic potential energy curves of the interacting states and relevant spin-orbit coupling matrix elements defined analytically by Expanded Morse Oscillators model reproduce 95% of experimental data field of the 39K133Cs isotopomer with a standard deviation of 0.004 cm-1 which is consistent with the uncertainty of the experiment. Reliability of the derived parameters was additionally confirmed by a good agreement between the predicted and experimental termvalues of 41K133Cs isotopomer. Calculated intensity distributions in the A ~ b --> X LIF progressions are also consistent with their experimental counterparts.Comment: 17 pages, 14 figure

Microwave analysis of the interplay between magnetism and superconductivity in EuFe2(As1−xPx)2 single crystals

We report on the microwave analysis of the interplay between magnetism and superconductivity in single crystals of EuFe_{2}(As_{1−x}P_{x})_{2}, accomplished by means of a coplanar waveguide resonator technique. The bulk complex magnetic susceptibility χ_{m} extracted through a cavity perturbation approach is demonstrated to be highly sensitive to the magnetic structure and dynamics, revealing two distinct magnetic transitions below the superconducting critical temperature. By a comparison with magnetic force microscopy maps, we ascribe the χ_{m}^{′′} peak observed at about 17 K to the transition from the ferromagnetic domain Meissner phase to the domain vortex-antivortex state, with the subsequent evolution of the domain structure at lower temperatures. The second χ_{m}^{′′} peak observed at 11 K reflects a specific high-frequency feature, connected to vortex-antivortex dynamics and eventual spin reorientation transition of the Eu^{2+} canted ferromagnetic subsystem. The two peaks merge and vanish upon application of an in-plane magnetic field, which is compatible with the presence of a quantum critical point below 1 T

Ex situ elaborated proximity mesoscopic structures for ultrahigh vacuum scanning tunneling spectroscopy

We apply ultrahigh vacuum Scanning Tunneling Spectroscopy (STS) at ultra-low temperature to study proximity phenomena in metallic Cu in contact with superconducting Nb. In order to solve the problem of Cu-surface contamination, Cu(50nm)/Nb(100nm) structures are grown by respecting the inverted order of layers on SiO2/Si substrate. Once transferred into vacuum, the samples are cleaved at the structure-substrate interface. As a result, a contamination-free Cu-surface is exposed in vacuum. It enables high-resolution STS of superconducting correlations induced by proximity from the underlying superconducting Nb layer. By applying magnetic field, we generate unusual proximity-induced superconducting vortices and map them with a high spatial and energy resolution. The suggested method opens a way to access local electronic properties of complex electronic mesoscopic devices by performing ex situ STS under ultrahigh vacuum. © 2014 AIP Publishing LLC

Josephson tunnel junctions with ferromagnetic \Fe_{0.75}\Co_{0.25} barriers

Josephson tunnel junctions with the strong ferromagnetic alloy \Fe_{0.75}\Co_{0.25} as the barrier material were studied. The junctions were prepared with high quality down to a thickness range of a few monolayers of Fe-Co. An oscillation length of $\xi_{F2}\approx 0.79\:{\rm {nm}}$ between 0 and $\pi$-Josephson phase coupling and a very short decay length $\xi_{F1}\approx 0.22\:{\rm {nm}}$ for the amplitude of the superconducting pair wave function in the Fe-Co layer were determined. The rapid damping of the pair wave function inside the Fe-Co layer is caused by the strong ferromagnetic exchange field and additional magnetic pair breaking scattering. Josephson junctions with Fe-Co barriers show a significantly increased tendency towards magnetic remanence and flux trapping for larger thicknesses $d_{F}$.Comment: contains 5 figure

Возможности магнитно-резонансной томографии в диагностике острого асептического сакроилиита у детей: клинический случай

The onset of progressive deficit in multiple sclerosis (MS) was often determined retrospectively with difficulties in diagnostic. This is a case report with subtle MS progression. Clinical and structural MRI anamnesis was complemented with multivoxel 1HMRS examination. The patient complained of the walking distance reducing, gradually increasing spasticity in the distal parts of lower extremities, unsteadiness when walking, clumsy movements. Choline and myoinositol levels were predominantly increased in the area of the cingulate gyrus versus other gray matter regions and the same picture was observed in adjacent white matter. Multivoxel 1H-MRS represents a diagnostic tool that can be very useful in complex diagnostic of MS progression. Measuring chemical-pathological changes diffusely in brain tissues may detect distinctive for progression metabolic patterns.В связи с трудностями диагностики момент начала накопления прогрессирующего дефицита при рассеянном склерозе (РС) часто определяется ретроспективно. Данная статья представляет собой описание клинического случая с труднораспознаваемым прогрессированием рассеянного склероза. Пациент обратился с жалобами на уменьшение дистанции ходьбы, постепенно нарастающая спастичность в дистальных отделах нижних конечностей, шаткость при ходьбе, неловкость движений. Клинический и структурный МРТ-анализ был дополнен мультивоксельной 1Н-МР-спектроскопией (1H-МРС). Уровни холина и миоинозитола были преимущественно повышены в области поясной извилины по сравнению с другими областями серого вещества, такая же картина наблюдалась в прилежащем к поясной извилине белом веществе. Мультивоксельная 1H-МРС представляет собой диагностический инструмент, который может быть очень полезен в комплексной диагностике прогрессирования рассеянного склероза. Диффузное измерение химико-патологических изменений в тканях головного мозга может выявить характерные для прогрессирования метаболические паттерны

Magnetization dynamics in dilute Pd<inf>1-</inf><inf>x</inf>Fe<inf>x</inf> thin films and patterned microstructures considered for superconducting electronics

© 2016 Author(s).Motivated by recent burst of applications of ferromagnetic layers in superconducting digital and quantum elements, we study the magnetism of thin films and patterned microstructures of Pd0.99Fe0.01. In this diluted ferromagnetic system, a high-sensitivity ferromagnetic resonance (FMR) experiment reveals spectroscopic signatures of re-magnetization and enables the estimation of the saturation magnetization, the anisotropy field, and the Gilbert damping constant. The detailed analysis of FMR spectra links the observed unexpectedly high reduced anisotropy field (0.06-0.14) with the internal anisotropy, points towards a cluster nature of the ferromagnetism, and allows estimating characteristic time scale for magnetization dynamics in Pd-Fe based cryogenic memory elements to (3 - 5) × 10 - 9 s