Fermi Energy Research Articles

Electronic structure and magnetothermal properties of two-dimensional ScCl.

Two-dimensional ferromagnetic materials with intrinsic half-metallic properties have strong application advantages in nanoscale spintronics. Herein, density functional theory calculations show that monolayer ScCl is a ferromagnetic metallic material when undoped (n = 0), and the transition from metal to half-metal occurs with the continuous doping of holes. On the contrary, as the concentration of doped electrons increases, the system will exhibit metallic characteristics, which is particularly evident from a variation in spin polarizability. Furthermore, we have discussed how doped carriers affect the shape of the Fermi surface and the Fermi velocity of electrons. Most importantly, Monte Carlo simulations show that the ScCl monolayer is particularly regulated by carrier concentration (n) and magnetic field (h). Additionally, trends in energy and magnetic exchange coupling in different magnetic configurations (AFM phase and FM phase) with different doping concentrations are presented. When n < -0.16, the material is not only a half-metallic material that easily flips the magnetic axis, but also proves to be a candidate ferromagnetic material that works stably at room temperature in terms of dynamic stability. In addition, the origin of magnetocrystalline anisotropy is analyzed, and the contribution of different orbitals to spin-orbit coupling is presented. Moreover, we note that when magnetic field is small (h < 1 T), the change in size has a significant effect on ferromagnetic phase transition. However, when the system size is large (size >15 nm), TC is less sensitive to magnetic field. In addition, hole doping and size effect will greatly affect the hC of the system, but when the hole doping exceeds the critical value (n = -0.16), its influence on the hysteresis loop is no longer obvious. These interesting magnetic phenomena and easily adjustable physical properties show us that monolayer ScCl will be a promising functional material.

Modeling the Temperature Dependence of Shubnikov-De Haas Oscillations in Light-Induced Nanostructured Semiconductors

In this work, the influence of light on the temperature dependence of transverse magnetoresistance oscillations is studied. A generalized mathematical expression that calculates the temperature and light dependence of the quasi-Fermi levels of small-scale p-type semiconductor structures in a quantizing magnetic field is derived. New analytical expressions have been found to represent the temperature dependence of transverse differential magnetoresistance oscillations in dark and light situations, taking into account the effect of light on the oscillations of the Fermi energy of small-scale semiconductor structures. A mathematical model has been developed that determines the light dependence of the second-order derivative of the transverse magnetoresistance oscillations of p‑type semiconductors with quantum wells by magnetic field induction. A new theory is proposed, which explains the reasons for the significant shift of the differential magnetoresistance oscillations along the vertical axis measured in the experiment for dark and light conditions.

Bending deformation modulation of the optoelectronic properties of molybdenum ditelluride doped with nonmetallic atoms X (X = B, C, N, O): a first-principles study.

A first-principles approach based on density functional theory was used to explore the effect of bending deformation on the electrical structure of molybdenum ditelluride doped with nonmetallic atoms X (X = B, C, N, and O). The study included alternate doping of nonmetallic atoms, as well as a comparison of the effects of intrinsic bending deformation and nonmetallic doping deformation. The results demonstrate that boron atom doping raises the Fermi energy level. Examining the energy band structure indicates that the intrinsic molybdenum ditelluride is a direct band gap semiconductor, which is transformed from a direct band gap to an indirect band gap after doping. We selected boron-doped systems for bending deformation and compared them with the intrinsic systems. With increasing deformation, all systems start to shift from semiconductor to metal. When the deformation reaches 8°, the energy levels fill and the electron energy increases. The intrinsically bent systems transition from direct band gap to indirect band gap and eventually to metal. The indirect band gap semiconductor-to-metal transition process occurs after the bending deformation of the boron-doped atoms. The analytical results show that the absorption and reflection peaks of the molybdenum ditelluride system are blue-shifted after the bending deformation of the boron-doped atoms. Under fundamental principles, this research depends on the density functional theory framework (DFT) using the CASTEP module in the Materials-Studio software. The plane-wave pseudopotential approach with modified gradient approximation and the Perdew-Burke-Ernzerhof (PBE) generalized function is used for structure optimization and total energy calculations of the X-doped (X = B, C, N, O) MoTe2 system at different shape variables. Geometry optimization of the 27-atom superlattice MoTe2 was carried out, followed by alternative doping of tellurium atoms in the molybdenum ditelluride with B, C, N, and O. In this paper, the intrinsic bending deformation and B-doping of molybdenum ditelluride were selected for deformation analysis. Intrinsic bending deformations and boron-doped molybdenum ditelluride with bending angles ranging from 2° to 8° were employed for deformation investigation. In Fig.1, pink is used to represent doped B atoms, orange is used to describe Te atoms, and green is used to represent Mo atoms. For the degree of deformation of molybdenum ditelluride, in this paper, it is expressed by the bending angle, i.e., the angle of the plane of molybdenum ditelluride after bending and deformation of a single layer of molybdenum ditelluride concerning the angle of the plane folded for the deformed plane. How to do it: For ease of presentation, the atomic chains are set to different colors. The purple part on both sides of the figure is bent and deformed, 3-5 atoms are fixed appropriately, and the middle part is deformed. On this basis, the bending deformation of intrinsically doped and boron-doped MoTe2 is comparatively analyzed. The effect of boron-doped atoms on the structure of MoTe2 is systematically investigated to study its structural stability and electronic structure. Fig.1 a1 and a2 The main and side views of intrinsic MoTe2; b1 and (b2) the main and side views of MoTe2 doped with boron atoms bent by 8°.

Revised Fowler–Dubridge model for multiphoton over-barrier electron emission from two-dimensional materials

We revise the Fowler–Dubridge model for multiphoton over-barrier photoemission from two-dimensional (2D) materials to include the effects of reduced dimensionality, non-parabolic, and anisotropic energy dispersion of 2D materials. Two different directions of electron emission are studied, namely, vertical emission from the surface and lateral emission from the edge. Our analytical model reveals a universal temperature scaling of Tβ with β = 1 for the surface emission over a wide class of 2D materials and β = 3/2 for the edge emission from the 2D material with anisotropic parabolic energy dispersion, which are distinct from the traditional scaling of β = 2 originally derived for the traditional bulk materials. Our comparison shows good agreement with two experiments of photoelectron emitted from graphene for both surface and edge emission. Our calculations also show that the photoelectron emission is more pronounced than the coexisting thermionic emission for materials with low temperature and Fermi energy. This model provides helpful guidance in choosing proper combinations of light intensity, temperature range, and type of 2D materials for the design of photoemitters, photodetectors and other optoelectronics.

A tunable flat terahertz lens using Dirac semimetals: a simulation study

We propose and design a flat and tunable terahertz lens achieved through a two-dimensional photonic crystal composed of an array of rods made of a Dirac semimetal placed in air as the background medium. The structure of interest is a graded index photonic crystal, made possible by the slight variations in the rods’ radii in a direction perpendicular to the direction of the light propagation. Dirac semimetals' ability to respond to variations in their Fermi energy level manifested as a change in the refractive index provides the tunability of our proposed lens. The interaction of electromagnetic waves with the designed structure is investigated for both transverse magnetic and transverse electric polarizations using two-dimensional finite-difference time-domain method.

Preparation and characterization studies of silica tin nanospheres from Indian rice husk for suitable photocatalytic applications

The synthesis of nanomaterials is advancing due to its ease of synthesis, inexpensiveness, nontoxicity, and renewability. In the present study, an eco-friendly sol–gel method was employed to prepare silica tin nanospheres from Indian rice husks. We used cetyl trimethyl ammonium bromide as the surfactant at room temperature. The calcination of the material at 1000 °C for 24 h gave nanospheres with a diameter of 3–5 nm. The PXRD pattern confirms that the material is amorphous. The FTIR analysis confirms the existing functional groups of silica tin nanospheres. The optical properties of silica tin nanospheres were evaluated using UV visible spectra analysis. The Energy gap of the silica tin nanospheres was calculated and it was found to be 4.85 eV. Using DLS measurements the size of the silica tin nanospheres was estimated to lie between 43 nm and 226 nm and the particles having 108 nm diameter showed an intensity of 90 %. The dielectric properties of silica tin nanospheres were studied in the range of 1 Hz to 1000 MHz at various temperatures. The dielectric properties of silica tin nanospheres were found to be significantly enhanced, especially in the low-frequency range due to quantum confinement. Besides, the values such as valency electron plasma energy, Penn energy, fermi energy, and electric polarizability were evaluated. From the SEM analysis it is observed that the material is nanosized sphere. Also, the SEM analysis reveals that the spherical structure has a high porous and uniformly agglomerated structure. The study of the elemental composition of silica tin nanospheres through XRF analysis has been carried out.

Localized electronic reconfiguration at CoNi-BTC-MOFs to accelerate oxygen evolution reaction

To efficiently control oxygen evolution reaction (OER) at electrocatalysts holds enormous promise for large-scale production of clean energy, but faces the scarcity of practical regulation strategies due to underexplored catalytic mechanism. Herein, a facile and feasible strategy is developed involving metal-metal super-exchange interaction to manipulate the electronic state configuration of catalysts, and the as-synthesized Ni-doped Co-1,3,5-benzenetricarboxylic acid Metal-Organic Frameworks (MOFs) only require an overpotential as low as 260 mV to reach a large current of 200 mA cm−2, which is much lower than 400 mV for the commercial RuO2 catalyst. The introduced Ni atoms lead to more broadly occupied states and d-band center close to the Fermi energy level for the spin-polarization of the electrons in Co atoms, thus decreasing the orbital occupancy to facilitate the adsorption/desorption of the reaction intermediates and lowering the rate-determining step barrier to accelerate OER. Our findings have an important paradigm role in the design of electrocatalysts with high performance for oxygen evolution reaction.

Ethanolamine gas sensors based on NdFeO3 modified hexagonal pyramid shaped ZnO nanocrystals

It is well known that two metal oxides can form depletion layers at the interface by constructing heterojunctions due to the different Fermi energy levels of each metal oxide, which can improve the carrier mobility and provide significant advantages for gas sensing. In this work, NdFeO3 nanoparticles were grown on ZnO with hexagonal cone structure by secondary hydrothermal method to successfully construct n-ZnO/p-NdFeO3 heterojunctions, and the crystal structures, oxygen vacancies, microstructures, optical properties, and gas-sensing properties of the ZnO/NdFeO3 composites were investigated. The ZnO/NdFeO3 sensors showed good ethanolamine (EA) The response characteristics of the ZnO/NdFeO3 sensor to ethanolamine (EA) with a concentration of 100 ppm EA at 240 °C (Rg/Ra) is about 25, which improves the response by a factor of 1.6 and 1.32 compared with that of NdFeO3 and ZnO. Meanwhile, it has excellent selectivity, good cyclic reproducibility, and durable long-term stability with response/recovery times of 19 s/49 s. The improved EA sensing performance of NdFeO3-modified ZnO, in addition to its large specific surface area due to its unique rough inhomogeneous structure, is also related to the higher concentration of oxygen vacancies at the ZnO/NdFeO3 interface after the composite. In addition, the construction of ZnO/NdFeO3 heterostructure brings more efficient carrier migration, which is favorable to the surface reaction and diffusion of EA molecules, and lowers the ZnO operating temperature, thus reducing the energy consumption. The ZnO/NdFeO3 composite sensor based on n-p heterojunction provides a valuable strategy for the detection of volatile organic compounds.

Refining Asymmetric Low‐Coordinated Fe‐N3 Motif to Boost Catalytic Ozonation Activity

AbstractIn the quest to boost the intrinsic activity of single‐atom catalysts (SACs), optimizing the electronic properties of metal centers and maximizing active sites play a pivotal role. Here, a facile surface molten salt‐assisted approach for fabricating porous iron‐nitrogen‐carbon catalysts enriched with catalytically accessible single‐atom motifs is reported. Multiple characterization analyses prove that abundant intrinsic defects are generated at the edge sites, resulting in the formation of thermally stable unstitched Fe‐N3 motif. Theoretical investigations unveil that the transition from Fe‐N4 to Fe‐N3 induces structural alteration, resulting in the convergence of Fe‐3d orbital energy to Fermi energy. The low‐coordinated Fe‐N3 motif exhibits higher activation ability, reinforcing its interaction with O3 and weakening the O‐O bond. This leads to a reduction in the reactivity of surface atomic oxygen barriers (O3‐to‐*O/*OO), ultimately achieving efficient catalytic oxidation of methyl mercaptan and its intermediates, achieving performance 20‐fold higher than intact Fe‐N4 catalysts and 625‐fold higher than commercial MnO2. These findings present a comprehensive approach for synthesizing SACs with fully accessible active sites and boosted electronic configurations to advance catalytic ozonation activity.

First-principles study of the effect of alkaline-earth metal doping on the intrinsic MoSe2 photovoltaic properties

In this study, the effect of alkaline-earth metal element doping on the photoelectric properties of intrinsic MoSe2 is systematically investigated based on the first-principles approach, and it is believed that the findings of this work will give some theoretical guidance for future research on MoSe2 doping modification. The results show that all the doping systems exhibit good stability, and Be atom doping has the lowest formation energy value, making the doping easier to produce. The doping of alkaline-earth metal elements resulted in some lattice distortion of MoSe2. Intrinsic MoSe2 is a semiconductor with a direct bandgap of 1.498[Formula: see text]eV, and the doping of alkaline-earth metal elements causes the bandgap value to decrease in each system, and the bandgap is the smallest when Be is doped. All doped systems exhibit P-type conducting properties. Compared with the intrinsic MoSe2, all doped systems have their conduction band fraction moved to the low-energy direction overall, and new density of states peaks appear near the Fermi energy level. These state density peaks mainly originate from the results contributed by the s-orbitals of each doping system Mo-4d, Se-4p, and each dopant atom. The analysis of the work function reveals that the work function of each doped system is smaller than the intrinsic MoSe2, then the energy required for the occurrence of electron leaps is reduced, which improves the electron mobility of the doped system. The Mulliken Population analysis shows that stable chemical bonds are formed between the doped alkaline-earth metal elements and the surrounding Se atoms. The examination of the optical characteristics demonstrated that, in comparison to the intrinsic MoSe2, all doped systems’ greatest dielectric absorption peaks were attenuated and moved toward the low-energy region; the doping of alkaline-earth metal elements broadened the light absorption edge of the intrinsic MoSe2. The absorption peaks of each doping system are shifted toward the low-energy region with the red-shift phenomenon, and the light absorption is good in the ultraviolet region.

Thermophysical Properties of Vanadium Melts and Discussion of Thermal Diffusivity in Mott’s Theory

The temperature dependence of density, normal spectral emissivity, heat capacity at constant pressure, and thermal conductivity of the V melt were measured with high accuracy using electromagnetic levitation in a static magnetic field. Surface vibration, translational motion, and convection of the electromagnetically levitated droplet sample were suppressed by the magnetic field. In the measurement of thermal conductivity, convection in the V-melt was sufficiently suppressed by the application of a field of 7 T or higher. In this study, the measured emissivity and thermal conductivity are compared with those evaluated using the free-electron models (Drude model and Wiedemann–Franz rule). Correlations between the density of states and thermal diffusivity at the Fermi energy of transition metals in the liquid state are investigated and the applicability of Mott's s–d scattering model is discussed.

Wafer-scale 30° twisted bilayer graphene epitaxially grown on Cu0.75Ni0.25 (111)

Twisted bilayer graphene (TBG) has been extensively studied because of its novel physical properties and potential application in electronic devices. Here we report the synthesis and characterization of 30° TBG naturally grown on Cu0.75Ni0.25 (111) film and investigate the electronic structure by angle-resolved photoemission spectroscopy. Compared with other substrates, our TBG with a wafer scale is acquired with a shorter growth time. The Fermi velocity and energy gap of Dirac cones of TBG are comparable with those of a monolayer on Cu0.85Ni0.15 (111). The signature of moiré lattices has not been observed in either the low-energy electron diffraction patterns or the Fermi surface map within experimental resolution, possibly due to different Cu and Ni contents in the substrates enhancing the different couplings between the substrate and the first/second layers and hindering the formation of a quasiperiodic structure.

Magnons in a two-dimensional Weyl magnet

The discovery of topological states of matter has led to a revolution in condensed-matter science. While a non-trivial band topology in a material is often associated with intriguing transport properties, much less attention has been given to the impact on spin dynamics and non-equilibrium magnetization states. Here, we provide evidence that a chiral asymmetric magnon dispersion in the two-dimensional Weyl magnet Fe/W(110) is related to the presence of Weyl fermions close to the Fermi energy and surface Fermi arcs. We find that the large anomalous Hall conductivity and the Dzyaloshinskii–Moriya interaction are attributed to the non-trivial band topology in the composite momentum-magnetization space. Our results show the direct impact of Weyl fermions on both the charge and spin dynamics in a two-dimensional magnet. Unveiling these principles can promote innovative technologies in magnonics by utilizing topological materials, where magnons and non-trivial topological electronic states can be manipulated through magnetization.

Origin of linear magnetoresistance in Bi2Te3 topological insulator: Role of surface state and defects

Connection between topological surface states (TSS) and large linear magnetoresistance (LMR) is established in tetradymite Bi2Te3 through tuning of native defects. Thorough analysis of temperature dependent synchrotron X-ray diffraction data quantifies 0-D, 1-D and 2-D defect concentrations. Plausible variation of antisite defects is explained via carrier concentration data. Resistivity data divulge contribution of mixed bulk and surface states in the synthesized samples. High Fermi velocity (∼106 ms−1) and low Fermi energy (∼14 meV) of carriers are obtained. Lower defect concentration sample emerges with high magnetoresistance (MR) and higher mobility. Weak antilocalization (WAL) effect, signature of TSS, is revealed from MR. Large (80%), non-saturating LMR along with ultrahigh mobility (∼1 m2V−1s−1) in Bi2Te3 supports the presence of TSS. Magnetoconductance data are fitted with Hikami-Larkin-Nagaoka equation, obtaining further insight on WAL effect. In addition, extracted parameters like disorder correlation length and coherence length explicate the role of defect density on LMR.

Triple-band graphene-based tunable electromagnetically induced transparency terahertz metamaterial with multi-frequency optical switching

A simple graphene-based terahertz metamaterial with the composite patterns of a π-shaped and a strip-shaped is proposed for realizing the electromagnetically induced transparency (EIT) effect. Three efficient transparent peaks with the average transparency strength of >85 % are achieved. The physical mechanism of the formation of the triple-band EIT effect is illustrated by the transmission spectra combined with the electric field diagrams of the transparent window and the transmission dip. Interestingly, upon changing the position of the strip-shape graphene and the distance between the vertical graphene, the triple-band EIT effect shifts to a dual-band and a single-band, respectively, illustrating the reason for the shifts using the electric field of peaks and dips. The Fermi energy level of graphene can be changed by biasing voltage to create a frequency shift of the resonance peaks of the transmission spectrum, and at the same time, six-frequency optical switching can be realized, which has a modulation degree of amplitude (MDA) of 94.6 %, 90.6 %, 98.1 %, 90.5 %, 97.6 %, and 89.4 %, respectively. These results indicate that the proposed multi-band terahertz metamaterials have great potential for applications in fields such as optical switching and sensing.

A first-principles study of the electronic structure and mechanical and optical properties of Mn-doped K2SiF6

The lattice constants, electronic structures, mechanical and optical properties of non-doped and Mn4+-doped K2SiF6 (KSF:Mn4+) were investigated using first-principles calculations. The calculated results show that Mn4+ doping enlarges the lattice constant and cell volume of KSF. Around the Fermi energy level, there is a decrease in the peak of density of states, significantly weakening the electron localization property. Mn4+ doping induces two impurity energy levels, causing a shift in the electronic states of KSF towards to the low-energy, thereby altering in the energy band structure. This alteration results in a narrower forbidden bandwidth, which reduces the photon energy required for electron transitions. Consequently, it increases the probability of electron transitions from the valence band to the conduction band, thereby enhancing the material's photocatalytic ability in the visible and ultraviolet regions. The pressure-volume relations are described using the Birch-Murnaghan's equation of state to calculate the bulk modulus of KSF and KSF:Mn4+, which is associated to the hardness of a material under particular conditions. This study provides a theoretical basis for a better understanding of the effects of Mn4+ doping on the mechanical properties, electronic structure and optical properties of KSF.

Density Functional Theory Unveils the Secrets of SiAuF3 and SiCuF3: Exploring Their Striking Structural, Electronic, Elastic, and Optical Properties.

In the quest for advanced materials with diverse applications in optoelectronics and energy storage, we delve into the fascinating world of halide perovskites, focusing on SiAuF3 and SiCuF3. Employing density functional theory (DFT) as our guiding light, we conduct a comprehensive comparative study of these two compounds, unearthing their unique structural, electronic, elastic, and optical attributes. Structurally, SiAuF3 and SiCuF3 reveal their cubic nature, with SiCuF3 demonstrating superior stability and a higher bulk modulus. Electronic investigations shed light on their metallic behavior, with Fermi energy levels marking the boundary between valence and conduction bands. The band structures and density of states provide deeper insights into the contributions of electronic states in both compounds. Elastic properties unveil the mechanical stability of these materials, with SiCuF3 exhibiting increased anisotropy compared to SiAuF3. Our analysis of optical properties unravels distinct characteristics. SiCuF3 boasts a higher refractive index at lower energies, indicating enhanced transparency in specific ranges, while SiAuF3 exhibits heightened reflectivity in select energy intervals. Further, both compounds exhibit remarkable absorption coefficients, showcasing their ability to absorb light at defined energy thresholds. The energy loss function (ELF) analysis uncovers differential absorption behavior, with SiAuF3 absorbing maximum energy at 6.9 eV and SiCuF3 at 7.2 eV. Our study not only enriches the fundamental understanding of SiAuF3 and SiCuF3 but also illuminates their potential in optoelectronic applications. These findings open doors to innovative technologies harnessing the distinctive qualities of these halide perovskite materials. As researchers seek materials that push the boundaries of optoelectronics and energy storage, SiAuF3 and SiCuF3 stand out as promising candidates, ready to shape the future of these fields.

Optical properties and luminescence behavior of Tb3+-Doped SiO2–Al2O3–BaO–BaF2 oxyfluoride glasses and glass ceramics

In this study, oxyfluoride glasses with chemical composition of 45SiO2–15Al2O3–10BaO–30BaF2-xTbF3 (x = 0.2, 0.4 and 0.6 (mole ratios)) were prepared through the conventional melt-quenching method. Raman and FTIR spectra as well as molar volume calculations proved the creation of more non-bridging oxygens (NBOs) in presence of more TbF3 content. Accordingly, absorption edge in UV–Vis spectra showed a slight red-shift to longer wavelengths. The glass with 0.4 mol ratios of TbF3, exhibited the highest photoluminescence emission and its green-to-blue intensity ratio was 0.66. Therefore, this sample was chosen and heat treated at 630, 650 and 675 °C to prepare glass ceramic samples. For the sample heat treated at 650 °C, photoluminescence intensity increased and green-to-blue intensity ratio reached 0.69. Also, lifetimes of green and blue emissions increased from 3.35 ms to 3.67 ms and from 2.95 ms to 3.10 ms, respectively, when the base glass heat treated at 650 °C. Formation of BaF2 nanocrystals in glass ceramics moved the UV–Vis absorption edge to longer wavelengths significantly. Increment of the weak and dangling bonds in crystallized samples reduced Fermi energy, indirect and direct optical band gap energies from 3.792 eV to 3.301 eV, from 3.522 eV to 3.093 eV and from 4.095 eV to 3.582 eV respectively, which led to higher semiconducting behaviors.

Electronic, optical, and thermoelectric characteristics of (Ae)xFBiS2 (Ae=Sr, Ba, and x=1.7) layered materials useful in optical modulator devices

The recent discovery of superconductivity behavior in the mother BiS2-layered compounds has captivated the attention of several physicists. The crystal structure of superconductors with alternate layers of BiS2 is homologous to that of cuprates and Fe-based superconductors. The full-potential linearized augmented plane-wave (FP-LAPW) technique was utilized to investigate the electronic structures and density of states in the vicinity of the Fermi energy of SrFBiS2 and BaFBiS2 compounds under the electron carriers doping. The introduction of electron doping (carries doping) reveals that the host compounds SrFBiS2 and BaFBiS2 exhibit features indicative of superconductivity. This carrier doping of SrFBiS2 and BaFBiS2 compounds (electron-doped) has a significant impact on the lowest conduction states near the Fermi level for the emergence of the superconducting aspect. The electron doping modifies and induces changes in the electronic structures with superconducting behavior in (Ae)1.7FBiS2(Ae=Sr,Ba) compounds. A Fermi surface nesting occurred under the modification of electrons (carriers) doping in the host compounds SrFBiS2 and BaFBiS2. Furthermore, the optical characteristics of the carrier-doped SrFBiS2 and BaFBiS2 compounds are simulated. Due to the anisotropic behavior, the optical properties of these materials based on BiS2 demonstrate a pronounced polarization dependency. The starting point at zero photon energy in the infrared region is elucidated by considering the Drude features in the optical conductivity spectra of SrFBiS2 and BaFBiS2 compounds, when the electron carriers doping is applied. It was clearly noticed that the spin-orbit coupling (SOC) influences the electronic band structures, density of states, Femi surface, and optical features because of the heavy Bismuth atom, which may disclose fascinating aspects. Further, we conducted simulations to assess the thermoelectric properties of these mother compounds. The two BiS2-layered compounds could be suitable for practical thermoelectric purposes and are highlighted through assessment of electrical conductivity, thermal conductivity, Seebeck coefficient, and power factor. As a result, we propose that the mechanisms of superconducting behavior in BiS2 family may pave new avenues for investigating the field of unconventional superconductivity. It may also provide new insights into the origin of high-Tc superconductivity nature.

Feasible Parameters of Ohmic Areas of YBaCuO Thin Films Switched via Moving Unstable Border between Superconducting and Normal States

A system of two equations based on one of the classical electricity laws was used to determine the sizes and temperatures of ohmic areas formed under action of overcritical nanosecond electrical pulses. Calculations were performed at five points for three experimentally obtained voltage–current (V-I) dependences for samples with the same geometry but different critical current density values. The system included two additional conditions to satisfy the known descriptive model of transition from superconducting (SC) to a normal (N) state—S-N switching—and to obtain physically acceptable solutions over the entire current range of V-I dependence. The solution for each point takes the form of a function, since the initial temperature increase of the primary channel across the film is entered as a parameter. Two modes of concentrated energy release in the channel were disclosed. Their random appearance leads to an unexpected degradation of the sample. As such, the obtained results correspond to the situations occurring during the experiments. The validity of applying additional conditions to the system is discussed. In the discussion, it is also explained at which moments the moving S-N border acquires the velocity of the order of ~106 m/s, comparable to the Fermi velocity. Consideration to describe the moving unstable S-N border as being constantly in a state of Richtmyer–Meshkov instability is presented.