Creation and annihilation of mobile fractional solitons in atomic chains

Localized modes in one-dimensional (1D) topological systems, such as Majonara modes in topological superconductors, are promising candidates for robust information processing. While theory predicts mobile integer and fractional topological solitons in 1D topological insulators, experiments so far have unveiled immobile, integer solitons only. Here we observe fractionalized phase defects moving along trimer silicon atomic chains formed along step edges of a vicinal silicon surface. By means of tunnelling microscopy, we identify local defects with phase shifts of 2π/3 and 4π/3 with their electronic states within the band gap and with their motions activated above 100 K. Theoretical calculations reveal the topological soliton origin of the phase defects with fractional charges of ±2e/3 and ±4e/3. Additionally, we create and annihilate individual solitons at desired locations by current pulses from the probe tip. Mobile and manipulable topological solitons may serve as robust, topologically protected information carriers in future information technology.

Protective Langmuir–Blodgett coatings based on long-chain fatty acids

The morphology and tribotechnical properties of Langmuir–Blodgett (LB) monolayers and multilayers of some fatty acids, such as nervonic (NA), cerotic (CA) and montanic acids (OCA), was investigated. It was established that the wear resistance of silicon surface coated by LB monolayer of OCA is greater by 11 and 1.3 times in comparison with the LB monomolecular films of NA and CA, respectively. The multilayer of OCA, formed by 140 layers, increases the stability of steel surface by 35 times.

Investigation of the effect of annealing on Si(100) substrate modified by Ga+ focused ion beam

In this work, we studied the effect of annealing the silicon surface on the morphology of focused ion beam modified areas. It was found that an increase in the ion beam accelerating voltage during surface treatment significantly affects the morphology and the appearance of the implanted material on the surface or its absence/evaporation during annealing. It is shown that an increase in number of ion beam passes leads to the formation of holes on the surface of the modified areas, which is a sign that significant damage to the substrate material has occurred.

Influence of laser-induced plasma parameters on the formation of laser-induced surface-periodic structures

The paper presents the results of processing a silicon surface with subpicosecond laser pulses under various exposure conditions. The variable conditions were: pressure in the working chamber, the speed of scanning the silicon surface with a laser beam and the laser pulse energy. Special attention was paid to the interaction of the laser-induced plasma plume with the surface of the processed material, with laser radiation and with the medium. The influence of the medium on the parameters of the laser-induced plasma is estimated. The result of this interaction is a change in the spatial characteristics of the laser-induced plasma channel, the period and type of the formed periodic surface structures, what is related to the change in the laser radiation passing through the medium at different pressures.

Enhancing Antibodies’ Binding Capacity through Oriented Functionalization of Plasmonic Surfaces

Protein A has long been used in different research fields due to its ability to specifically recognize immunoglobulins (Ig). The protein derived from Staphylococcus aureus binds Ig through the Fc region of the antibody, showing its strongest binding in immunoglobulin G (IgG), making it the most used protein in its purification and detection. The research presented here integrates, for the first time, protein A to a silicon surface patterned with gold nanoparticles for the oriented binding of IgG. The signal detection is conveyed through a metal enhanced fluorescence (MEF) system. Orienting immunoglobulins allows the exposition of the fragment antigen-binding (Fab) region for the binding to its antigen, substantially increasing the binding capacity per antibody immobilized. Antibodies orientation is of crucial importance in many diagnostics devices, particularly when either component is in limited quantities.

Variation of the silicon optical parameters after rapid heat treatment

The results of the effect of rapid heat treatment on the optical characteristics of a silicon wafer surface in the region of the G-point in the Brillouin zone are presented for different types of silicon wafers conductivity, their doping level, the covalent radii of dopants and the crystallographic orientation of the wafer surface. The absorption coefficient and refractive index of the initial 100 mm diameter samples KDB-12 <100>, KDB-10 <111>, KDB-0.005 <100> and KES-0.015 <100>, underwent standard chemical-mechanical polishing, was measured on a Uvisel 2 ellipsometer (Horiba Scientific, France) in the spectral range 0.6–6.0 eV (200–2100 nm) before and after rapid heat treatment. The incidence angle of the light beam was 70° relative to the sample plane. It is shown that the changes in the optical characteristics of the silicon surface in the spectral region of the location of the G-point in the Brillouin zone after rapid heat treatment is due to a decrease in the surface deformation potential due to solid-phase recrystallisation of the mechanically damaged layer. It has been established that carrying out the rapid heat treatment of silicon samples with a high boron concentration leads to a more significant decrease in the refractive index and absorption compared with silicon with a low boron concentration, due to an increase in the depletion of the silicon surface with boron as a result of diffusion processes at the silicon – silicon dioxide interface.