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Spin gapless semiconductor (SGS) has attracted much attention since its theoretical prediction, while concrete experimental hints are still lacking in the relevant Heusler alloys. Here in this work, by preparing the series alloys of Mn2CoGa1−xAlx (x = 0, 0.25, 0.5, 0.75, and 1), we identified the vanishing of the anomalous Hall effect in the ferromagnetic Mn2CoGa (or x = 0.25) alloy in a wide temperature interval, accompanying with growing contribution from the ordinary Hall effect. As a result, comparatively low carrier density (1020 cm−3) and high carrier mobility (150 cm2/V s) are obtained in the Mn2CoGa (or x = 0.25) alloy in the temperature range of 10–200 K. These also lead to a large dip in the related magnetoresistance at low fields. However, in a high Al content, although the magnetization behavior is not altered significantly, the Hall resistivity is, instead, dominated by the anomalous one, just analogous to that widely reported in Mn2CoAl. The distinct electrical-transport behavior of x = 0 and x = 0.75 (or 1) is presently understood by their possible different scattering mechanism of the anomalous Hall effect due to the differences in the atomic order and conductivity. Our work can expand the existing understanding of the SGS properties and offer a better SGS candidate with higher carrier mobility that can facilitate the application in the spin-injected related devices. [ABSTRACT FROM AUTHOR]

The generation of hydrogen fuel, and wastewater treatment according to solar-driven catalysis possesses considerable prospective for establishing a carbon-neutral and ecologically sound power infrastructure. Driven by this problem, we suggest in this study, adopting a simple impregnation method, a customized association of CoAl-LDH and graphitic carbon nitride (CN), a visible light active narrow and wide band gap semiconductors. Several characterization approaches were implemented to understand the CoAl-LDH@g-C 3 N 4 (CACN) composites' physiochemical and optical features. The CACN hetero structural forms exhibited significantly improved solar light-induced photocatalytic H 2 generation and dye pollutants decomposition in contrast with pristine materials. The most effective catalyst 5 wt% CoAl-LDH@g-C 3 N 4 (5-CACN) generated the highest hydrogen (∼430.7 μmolg−1h−1), which is 11.9-fold H 2 production efficiency compared with CN and depicted significant Brilliant black dye removal efficacy via photocatalytic degradation (up to ∼79%). This was primarily ascribed to the development of the Type-II CACN heterojunctions, which promoted the separation of charges and expanded the abundance of surface-active sites while absorbing the visible spectrum of solar light. To examine the photocatalytic proficiency for H 2 production and dye pollutant removal over CoAl-LDH@g-C 3 N 4 heterojunction nanocomposites synthesized via a facile impregnation approach and plausible schematic photocatalytic mechanism for H 2 production and Brilliant black dye pollutant removal under visible photons illumination. [Display omitted] • A facile single-step hydrothermal method was employed to synthesize the CoAl-LDH nanotextures. • Type-II heterojunction CoAl-LDH@g-C 3 N 4 composites were prepared via a simple impregnation approach. • Type-II heterojunction CoAl-LDH@g-C 3 N 4 composites display an enhanced H 2 production during sunlight illumination. • Type-II heterojunction CoAl-LDH@g-C 3 N 4 depicts a significantly superior photocatalytic degradation of Brilliant Black dye in a water sample. • Plausible mechanism of Type-II heterojunction CoAl-LDH@g-C 3 N 4 for H 2 production and photocatalytic degradation of Brilliant Black dye. [ABSTRACT FROM AUTHOR]

We study the spin-polarized electron transport properties of hybrid BN–C nanotubes (BN–CNTs) in their pristine form and with Stone–Wales defects, namely, Cx(BN)10−x, using combined first-principles density functional theory and quantum transport simulations. We show that the band structures of pristine BN–CNTs can be sensitively tuned by their composition, transiting from the nonmagnetic semiconductor to half-semimetal and finally to a narrow gap semiconductor with increasing x. The spin-dependent current–voltage characteristics are sensitively modulated by x in the hybridized Cx(BN)10−x. The SW defect acts as an active scattering center for BN–CNTs, which decreases the overall conductance of nanotubes. Remarkably, a spin-filtering effect (SFE) with nearly 96% filtering efficiency is observed in C4(BN)6, and such a high SFE remains robust even in the presence of Stone–Wales defects. These results reveal the potential role of hybrid BN–CNT as a building block for spintronic device technology. [ABSTRACT FROM AUTHOR]

A metal‐rich niobium oxyiodide was prepared by soft reduction of NbI4. The structure of the new compound Nb4OI10 was determined by single‐crystal X‐ray diffraction and contains a rectangular Nb4(μ4‐O) cluster that is interconnected into layers by iodide ligands. The local structure of the Nb4OI10 cluster bears a close relationship to a defect Nb6I11 structure. The two‐dimensional van der Waals material ∞2[ ${{}_{{\rm \infty }}{}^{2}[}$ Nb4OI8I4/2] is a small band‐gap semiconductor (<1 eV), as analysed by electrical conductivity measurements, photoresponse, experimental band gap determination, and band structure calculation. [ABSTRACT FROM AUTHOR]

Topological materials usually possess protected gapless states in either the boundary or bulk, exhibiting various properties such as spin-momentum locking, Klein tunneling, Fermi arcs and so on. Database searches using symmetry data at high-symmetry points have catalogued thousands of topological materials revealing a magnitude of band nodes (BNs) at high-symmetry points or lying within high-symmetry lines/planes. A complete mapping from symmetry data (namely, representation of little group) in any BN to the k ⋅ p model characterizing low-energy Hamiltonian around the BN (and from the k ⋅ p model to concrete BN, inversely), is expected to complete the characterization of all BNs and gapless states. Here we first review recent progress on classifying BNs by systematically and automatically constructing k ⋅ p models based on recently completed tabulation of all irreducible (co-)representation matrices of little groups of the 1651 magnetic space groups. As one indispensable input in constructing a symmetry-allowed and generic k ⋅ p model, the expansion order, has been carefully and systematically truncated for any BN to a reasonable nonzero integer, by comparing the emanating nodal structure (ENS, including nodal point, nodal line and nodal surface) near the BN obtained by the explicitly constructed k ⋅ p model and that by pure symmetry analysis using compatibility relations (CRs). Owing to the progress, we are able to summarize all 25 different configurations of ENS near BN required by CRs, provide a complete mapping from k ⋅ p model to its realization around BN, and the corresponding ENS by CRs in an accessible file, and also reveal the protection mechanism of additional nodal lines that escape conventional analysis by CRs and is only predictable by constructing k ⋅ p model. The symmetry-based classification results on all BNs could facilitate large-scale materials prediction and hold promise for realizing topological semimetals suitable for device applications. [ABSTRACT FROM AUTHOR]

Recently, bulk Mg3X2 (X=As, Sb) have been intensively studied for their unique properties for thermoelectric use. However, studies on their two-dimensional counterparts are not sufficient. In this work, we systematically investigated the electronic, mechanical, vibrational, and piezoelectric properties of Mg3X2 (X = As, Sb) monolayers. The results indicate that both monolayers have negative formation energies with dynamical and mechanical stability. Mg3As2 monolayer is a narrow band gap semiconductor, while Mg3Sb2 monolayer is an indirect one. The origin of the band structure was revealed by the calculated partial density of states. The bonding property of both monolayers was analyzed by different methods. Elastic constants were obtained by density functional perturbation theory, and the related physical quantities were derived and analyzed. In-plane strengths along the zigzag and armchair directions of both materials were calculated, and the fracture mechanisms were uncovered. The vibrational modes at the Brillouin center were classified through group theory analysis, and the corresponding eigenvectors and frequencies were calculated and presented. Infrared vibrational spectra were simulated, and the reason for the vanishment of some infrared peaks was disclosed. Piezoelectric and dielectric coefficients were also computed and discussed. [ABSTRACT FROM AUTHOR]

Two highly uniform heterometallic photo-catalysts afforded by polyoxometalate synthons realize ultra-efficient hydrogen evolution of 2873 μmol g-1h−1, approaching triple times that of CdS and nearly sextuple times that of MoS 2. [Display omitted] • Two new highly dispersed bimetallic/trimetallic sulfide materials were prepared. • Showing ultra-efficient photocatalytic hydrogen evolution. • The efficient hydrogen evolution can run up to 2873 μmol g-1h−1. • The photocatalytic performance is much higher than most similar photocatalysts. • Providing a promising direction for the development of efficient photocatalysts. MoS 2 -based materials have emerged as photoelectric semiconductors characterized by a narrow band gap, high capacity for absorbing visible light, and reduced H 2 adsorption energy comparable to Pt. These attributes render them appealing for application in photocatalytic hydrogen production. Despite these advantages, the widespread adoption of MoS 2 -based materials remains hindered by challenges associated with limited exposure to active sites and suboptimal catalytic hydrogen production efficiency. To address these issues, we have designed and synthesized a new class of highly dispersed bimetallic/trimetallic sulfide materials. This was achieved by developing polyoxometalate synthons containing Ni-Mo elements, which were subsequently reacted with thiourea and CdS. The resulting Ni 3 S 2 -MoS 2 and Ni 3 S 2 -MoS 2 -CdS materials achieve photocatalytic hydrogen production rates of 2770 and 2873 μmol g–1h−1, respectively. Notably, the rate of 2873 μmol g–1h−1 for Ni 3 S 2 -MoS 2 -CdS surpassed triple (3.23 times) the performance of CdS and nearly sextuple (5.77 times) that of single MoS 2. These materials outperformed the majority of MoS 2 -based photocatalysts. Overall, this study introduces a straightforward methodology for synthesizing bimetallic/trimetallic sulfides with enhanced photocatalytic H 2 evolution performance. Our findings underscore the potential of transition metal sulfide semiconductors in the realm of photocatalysis and pave the way for the development of more sustainable energy production systems. [ABSTRACT FROM AUTHOR]

The structural stability, elastic, optoelectronic, and thermoelectric characteristics of anti‐perovskites Na3XO (X = Cu, Ag) have been studied using density functional theory (DFT). The computed formation energy suggests these materials' potential synthesis and thermal stability. The structural and elastic properties of Na3CuO and Na3AgO anti‐perovskite compounds were analyzed using the Perdew–Burke–Ernzerhof (GGA‐PBE) generalized gradient potential approximation. The electronic and thermoelectric properties are calculated using the TB‐mBJ approximation. The materials are identified as direct narrow band gap semiconductors with band gaps of 0.65 and 0.43 eV. The analysis of two‐dimensional charge density contours indicates that Na3CuO and Na3AgO have a mixed bonding character, as validated by the investigation of electron charge density. We analyzed the optical properties of Na3CuO and Na3AgO, including dielectric function, refractive index, absorbance, optical reflectivity, and energy loss, using photon energy up to 6 eV. The investigated thermoelectric characteristics demonstrate figure of merit (ZT) values of 0.58 and 0.56 at room temperature. Consequently, the analyzed anti‐perovskites might address waste heat management requirements and sustainable energy solutions. [ABSTRACT FROM AUTHOR]

The bandgap modulation and electronic properties modulation of two-dimensional HfSi2N4 monolayer induced by strain, electric field and atomic adsorption are studied by first principles. The HfSi2N4 monolayer was found to be dynamically, thermally, and mechanically stable at equilibrium, and it is a direct semiconductor with a bandgap of 1.87 eV. The bandgap of the HfSi2N4 monolayer can be precisely modulated by strain. Under the action of strain, HfSi2N4 monolayer not only transforms from direct semiconductor to indirect semiconductor, but also improves the absorption of visible light. An external electric field in the 0–0.5 eV/Å range can also modulate the bandgap of HfSi2N4 monolayer from 1.87 eV to 0 eV, and most importantly, at an external electric field of 0.5 eV/Å, HfSi2N4 monolayer shows the characteristics of spin gapless semiconductor. The calculated adsorption energy shows that the structures of H, O and F atoms adsorbed by HfSi2N4 monolayer can all exist stably. The bandgap of the configuration after adsorption of O and F atoms is significantly reduced compared with that of HfSi2N4 monolayer. Furthermore, the HfSi2N4 monolayer after adsorption of H and F atoms is transformed into a magnetic semiconductor. Method: All calculations were performed using Vienna ab initial simulation package, The electronic structure, mechanical properties, electronic properties and other properties were carried out using generalized gradient approximation (GGA-PBE), supplemented by HSE06 and GGA + U. The total-energy and force convergence are less than 10–6 eV and 0.001 eV/Å, respectively. The vacuum on the z-axis is selected 20 Å. The vdW interactions were corrected using the Grimme scheme (DFT-D3). [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) have attracted significant interest because of their tunable bandgaps, which enable numerous applications in fields such as photovoltaics, biomedicine, and materials science. This study explores various core electron treatments in the density functional theory (DFT) analysis of II-VI semiconductor quantum dots and their bulk counterparts. We compared All-electron (AE), Effective Core Potential (ECP), All-Electron Relativistic (AER), and DFT-Semicore pseudopotential (DSPP) treatments. Our findings indicate that the AE treatment aligns closely with the experimental results for smaller QDs, whereas the accuracy of DSPP increases with larger QDs. DSPP provides an optimal balance between computational efficiency and accuracy, making it suitable for studying II-VI QDs. Notably, the bandgap behavior varies, being direct for zinc and cadmium chalcogenides, whereas mercury chalcogenides are zero-gap semiconductors (semimetals). The inner bonds of the QDs exhibit an ionic character, whereas the terminal bonds display a covalent character. This study enhances our understanding of the structural and electronic properties of II-VI quantum QDs, aiding their application in various technologies. [ABSTRACT FROM AUTHOR]

This paper reports first-principles calculations on nanosheets of Ge–Sb–Te compounds, namely Sb 2 Te 3 , GeSb 2 Te 4 and Ge 2 Sb 2 Te 5 under two crystalline atomic stakings S1 and S2. Sb 2 Te 3 , GeSb 2 Te 4 and Ge 2 Sb 2 Te 5 -S1 are semiconductors with a narrow band gap ranging between 0.7 and 0.74 eV as evaluated with the HSEsol functional. The transport properties have been investigated by Boltzmann transport theory together with deformation potential theory. The strain effects on their electronic and thermoelectric properties as well as on their dynamical properties have been investigated. A valence band convergence is found in the equilibrium structures, which is an efficient approach to improve the thermoelectric performance of materials. Sb 2 Te 3 , GeSb 2 Te 4 and Ge 2 Sb 2 Te 5 -S1 possess high TE performance in a wide range of temperature, and the highest values of zT are 2.94, 2.63 and 2.27, respectively. [ABSTRACT FROM AUTHOR]

To investigate the possibility of p-type doping of α-SrSi2, a promising as an eco-friendly thermoelectric material, the energy changes of substitutions of the Si site of α-SrSi2 by group 13 elements were evaluated using first-principles calculations. It is found that Ga doping was the most energetically favorable dopant while In is the most unfavorable. We examined the synthesis of Ga- and In-doped α-SrSi2 using the vertical Bridgeman method and investigated their thermoelectric properties. The Ga atoms were doped to α-SrSi2 successfully up to 1.0 at. %, while In atoms could not be doped as suggested by calculations. For experimental prepared Ga-doped samples, the carrier density was observed to increase with Ga doping, from 3.58 × 1019 cm−3 for undoped α-SrSi2 to 4.49 × 1020 cm−3 for a 1.0 at. % Ga-doped sample at 300 K. The temperature dependence of carrier concentrations was observed to change from negative to positive with increasing Ga content. In addition, the temperature dependence of the Seebeck coefficient was also observed to change from negative to positive with increasing Ga content. The results indicate that α-SrSi2 undergoes a semiconductor–metal transition with Ga doping. The power factor for the undoped sample was quite high, at 2.5 mW/mK2, while the sample with 0.3 at. % Ga had a value of 1.1 mW/mK2 at room temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • The CeO 2-x /C 3-y N 4 /Ce(CO 3)(OH) double S-scheme heterojunctions with atomic vacancies tunable band gap are designed and fabricated. • The novel double S-scheme photogenerated electron-hole (e--h+) transfer path is found. • This study opens a window for the design of double S-scheme heterojunctions towards photocatalytic ENR decomposition. Building narrow band gap semiconductors and fast separation of photogenerated electron-hole (e--h+) structures are of great significance for photocatalytic process. In this contribution, the CeO 2-x /C 3-y N 4 /Ce(CO 3)(OH) double S-scheme heterojunctions with atomic vacancies tunable band gap (2.54 eV) have been designed and fabricated as a boost photocatalyst for enrofloxacin (ENR) photodegradation. Compared with the control samples, the experimental results indicate that the typical sample (CeO 2-x /C 3-y N 4 /Ce(CO 3)(OH)-2) achieves the highest ENR photodegradation efficiency (93.6 %) in 240 min under a pH of 6, and the possible photodegradation pathways are also proposed. The superior performance is ascribed to the CeO 2-x /C 3-y N 4 /Ce(CO 3)(OH) double S-scheme heterojunctions for selective recombination of photogenerated electrons with weak-reduction ability in conduction band (CB) of CeO 2-x , C 3-y N 4 and the photogenerated holes with weak-oxidation nature in valance band (VB) of C 3-y N 4 , Ce(CO 3)(OH), which increase the retention rate of photogenerated electrons in CB of Ce(CO 3)(OH) and photogenerated holes in VB of CeO 2-x to degrade ENR. This is the first systematic study of CeO 2-x /C 3-y N 4 /Ce(CO 3)(OH) double S-scheme heterojunctions for ENR photodegradation. [ABSTRACT FROM AUTHOR]

To investigate the possibility of p-type doping of α-SrSi2, a promising as an eco-friendly thermoelectric material, the energy changes of substitutions of the Si site of α-SrSi2 by group 13 elements were evaluated using first-principles calculations. It is found that Ga doping was the most energetically favorable dopant while In is the most unfavorable. We examined the synthesis of Ga- and In-doped α-SrSi2 using the vertical Bridgeman method and investigated their thermoelectric properties. The Ga atoms were doped to α-SrSi2 successfully up to 1.0 at. %, while In atoms could not be doped as suggested by calculations. For experimental prepared Ga-doped samples, the carrier density was observed to increase with Ga doping, from 3.58 × 1019 cm−3 for undoped α-SrSi2 to 4.49 × 1020 cm−3 for a 1.0 at. % Ga-doped sample at 300 K. The temperature dependence of carrier concentrations was observed to change from negative to positive with increasing Ga content. In addition, the temperature dependence of the Seebeck coefficient was also observed to change from negative to positive with increasing Ga content. The results indicate that α-SrSi2 undergoes a semiconductor–metal transition with Ga doping. The power factor for the undoped sample was quite high, at 2.5 mW/mK2, while the sample with 0.3 at. % Ga had a value of 1.1 mW/mK2 at room temperature. [ABSTRACT FROM AUTHOR]

Quantum computing offers the potential to revolutionize information processing by exploiting the principles of quantum mechanics. Among the diverse quantum bit (qubit) technologies, silicon‐based semiconductor spin qubits have emerged as a promising contender due to their potential scalability and compatibility with existing semiconductor technologies. In this paper, the latest developments of spin qubits in gate‐defined semiconducting nanostructures made of silicon and germanium, starting from the basic properties of electron and hole states in group‐IV semiconductors, are reviewed. Specifically, various nanostructures that exploit their unique microscopic properties for qubit implementations, elaborating on the advances and challenges in experiments, are discussed. Strategies for enhancing qubit performance, such as designing new nanostructures and identifying suitable operating points, particularly those involving the valleys of electron qubits and the heavy‐hole–light‐hole mixing of hole qubits, are also highlighted. This comprehensive review thus provides valuable insights into the current state‐of‐the‐art in semiconductor quantum computing and suggests avenues for future research. [ABSTRACT FROM AUTHOR]

Developing high-efficiency photothermal seawater desalination devices is of significant importance in addressing the shortage of freshwater. Despite much effort made into photothermal materials, there is an urgent need to design a rapidly synthesized photothermal evaporator for the comprehensive purification of complex seawater. Therefore, we report on all-in-one FeO x -rGO photothermal sponges synthesized via solid-phase microwave thermal shock. The narrow band gap of the semiconductor material Fe 3 O 4 greatly reduces the recombination of electron-hole pairs, enhancing non-radiative relaxation light absorption. The abundant π orbitals in rGO promote electron excitation and thermal vibration between the lattices. Control of the surface hydrophilicity and hydrophobicity promotes salt resistance while simultaneously achieving the purification of various complex polluted waters. The optimized GFM-3 sponge exhibitedan enhanced photothermal conversion rate of 97.3% and a water evaporation rate of 2.04 kg/(m2·hr), showing promising synergistic water purification properties. These findings provide a highly efficient photothermal sponge for practical applicationsof seawater desalination and purification,as well as develop a super-rapid processing methodology for evaporation devices. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, a graphene (GR)/monolayer (ML) blue phosphorous (Blue P)/GR selector was studied based on the first-principles theory. Due to different contact edges, four GR–Blue P lateral heterojunctions were constructed, namely, armchair–armchair (A–A), zigzag–armchair (Z–A), armchair–zigzag (A–Z), and zigzag–zigzag (Z–Z). As demonstrated by the binding energy and Mulliken population, we found that the Z–Z heterojunction was relatively stable. Furthermore, a GR/Blue P/GR selector based on the Z–Z heterojunction interface was proposed with a nonlinear (NL) coefficient is 105. However, the drive current of this device was insufficient. A P atom of the resistive layer was separately substituted with four different atoms (Ni, Cu, N, and Cl) to effectively improve selector performance. The energy band structure was half-metallic when doped with Ni or Cu while the others still maintained semiconductor characteristics, and the bandgap was significantly reduced. The Schottky barrier height and width of the interface (GR–Blue P), with Cl as the substituted impurity, were the smallest, leading to a three order of magnitude increase in the NL coefficient. The calculation shows that GR/Blue P/GR devices can be integrated as selectors in Resistive switching Random Access Memory (RRAM) arrays. This work also has a certain guiding significance for manufacturing new types of two-dimensional lateral selector apparatuses. [ABSTRACT FROM AUTHOR]

Though the high breakdown electric field of wide-bandgap semiconductors is usually attributed to their large bandgap, the impacts of other band structure parameters and scattering processes on impact ionization phenomena have not been clarified yet. This study computationally analyzes the effects of band structures and scattering rates on the high-field carrier transport properties such as impact ionization coefficients and drift velocity in wide-bandgap semiconductors. For that purpose, this study adopts Monte Carlo simulations in which the E – k dispersion and scattering rates are directly tuned. Simulations with varied band structures indicate that an average of the group velocity in the whole Brillouin zone is a dominant factor determining the impact ionization coefficients rather than the effective mass at the band edge. In addition, the Brillouin zone width has critical impacts when Bloch oscillations occur, which significantly suppress impact ionization. As for scattering mechanisms, the roles of inelastic scattering processes including impact ionization in energy relaxation are discussed. It is also revealed that elastic scattering contributes to energy relaxation processes through transitions of electrons to higher bands. This mechanism leads to the unintuitive positive temperature dependence of impact ionization coefficients when Bloch oscillations occur. These results obtained by the theoretical analyses in this study can serve as basic physical insight to understand the behaviors of impact ionization coefficients in wide-bandgap semiconductors. [ABSTRACT FROM AUTHOR]

Most cubic semiconductors have threefold degenerate p-bonding valence bands and nondegenerate s-antibonding conduction bands. This allows strong interband transitions from the valence to the conduction bands. On the other hand, intervalence band transitions within p-bonding orbitals in conventional p-type semiconductors are forbidden at k = 0 and, therefore, weak, but observable. In gapless semiconductors, however, the s-antibonding band moves down between the split-off hole band and the valence band maximum due to the Darwin shift. This band arrangement makes them three-dimensional topological insulators. It also allows strong interband transitions from the s-antibonding valence band to the p-bonding bands, which have been observed in α -tin with Fourier-transform infrared spectroscopic ellipsometry [Carrasco et al., Appl. Phys. Lett. 113, 232104 (2018)]. This manuscript presents a theoretical description of such transitions applicable to many gapless semiconductors. This model is based on k → ⋅ p → theory, degenerate carrier statistics, the excitonic Sommerfeld enhancement, and screening of the transitions by many-body effects. The impact of nonparabolic bands is approximated within Kane's 8 × 8 k → ⋅ p → -model by adjustments of the effective masses. This achieves agreement with experiments. [ABSTRACT FROM AUTHOR]

The topological magnetoelectric effect (TME) is a hallmark response of the topological field theory, which provides a paradigm shift in the study of emergent topological phenomena. However, its direct observation is yet to be realized due to the demanding magnetic configuration required to gap all surface states. Here, we theoretically propose that axion insulators with a simple ferromagnetic configuration, such as the MnBi2Te4/(Bi2Te3)n family, provide an ideal playground to realize the TME. In the designed triangular prism geometry, all the surface states are magnetically gapped. Under a vertical electric field, the surface Hall currents give rise to a nearly half-quantized orbital moment, accompanied by a gapless chiral hinge mode circulating in parallel. Thus, the orbital magnetization from the two topological origins can be easily distinguished by reversing the electric field. Our work paves the way for direct observation of the TME in realistic axion-insulator materials. [ABSTRACT FROM AUTHOR]

The optical properties and Landau quantisations in twisted bilayer graphene are investigated using a generalised tight-binding model that takes into account all interlayer and intralayer atomic interactions in the Moire superlattice. The system is a zero-gap semiconductor with double-degenerate Dirac-cone structures, and saddle-point energy dispersions appear at low energies for small twisting angles. The magnetic quantisation phenomena in this system are rich and unique, with Landau-level subgroups specified owing to specific Moire zone folding through modulation of the stacking angles. The Landau-level spectrum shows hybridised characteristics associated with those in monolayer, as well as AA and AB stackings. The detailed analysis explores the complex relations among the different sublattices on the same and different graphene layers. [ABSTRACT FROM AUTHOR]

We studied the structural, electronic, phonon spectrum and thermoelectric properties of ternary LuMSb (M = Ni, Pd, Pt) half Heusler compounds by using first principles method. The electronic properties are calculated via energy band structure and density of states by using GGA + U approximation. The calculations reveal that the replacement of Ni with Pd and Pt, energy gap decreases and LuNiSb, LuPdSb are found to have narrow indirect band gaps and exhibit semiconducting nature, while LuPtSb is found to be a gapless semiconductor. Phonon band structure calculations give only positive values of phonon frequency indicating the dynamically stability of these compounds. The thermoelectric properties have been computed using semi‐classical Boltzmann transport theory. We found high Seebeck coefficient (S) and high power factor (PF) for LuNiSb and LuPdSb compounds in the whole temperature range. The ZT values of LuNiSb and LuPdSb are high in general and reach a maximum of 0.67 and 0.69 at 450 K, respectively, whereas 0.39 is the maximum ZT value for LuPtSb at the same temperature. These findings propose LuNiSb and LuPdSb compounds as promising materials for thermoelectric applications at room temperature. [ABSTRACT FROM AUTHOR]

Herein, the electronic, magnetic, and optical properties of direct‐band semiconducting SiP monolayers (MLs) doped with 3d transition‐metal (TM) atoms are investigated using first‐principles calculations. The results indicate that TM (TM = Sc, Ti, Co, Ni, Cu, and Zn)‐doped SiP MLs are nonmagnetic, while TM (TM = V, Cr, Mn, Fe)‐doped ones exhibit prominent magnetic moments. Specifically, V‐, Cr‐, and Fe‐doped SiP MLs are magnetic semiconductors and Mn‐doped SiP ML is a spin gapless semiconductor, where the contributions of the TM atoms to magnetic moments are dominant and the contributions of the nearest Si and P atoms are either small or negligible. Furthermore, the TM (TM = V, Cr, Mn, Fe) doping can enhance the carrier mobility in certain directions and result in highly in‐plane anisotropic mobility behaviors. In addition, the TM (TM = V, Cr, Mn, Fe) doping can not only broaden the optical absorption range of SiP ML to the infrared region, but also enhance the optical absorption coefficients of SiP ML in the visible region. These results provide insights into the TM doping effect on the electronic, spintronic, and optical properties of SiP MLs and may be useful for related applications based on SiP MLs. [ABSTRACT FROM AUTHOR]

The efficacy of sonodynamic therapy (SDT) mainly relies on the sonosensitizers, which generate reactive oxygen species (ROS) upon ultrasound (US) stimulation. However, the limited availability of high‐efficiency sonosensitizers hampers the therapeutic effectiveness of SDT as a standalone modality. In this work, a robust sonodynamic and gas cancer therapeutic platform is constructed based on strontium (Sr) doped barium titanate (BST) piezoelectric nanoparticles functionalized with L‐arginine (BST@LA). The doping of Sr into A site of the ABO3 piezoelectric nanocrystals not only introduces oxygen vacancies into the nanoparticles and enhance the intrinsic piezoelectricity, but also narrows the semiconductor band gap and enhances charge carrier migration, all of which facilitate the sonodynamic production of superoxide anion (•O2−) and hydroxyl radical (•OH). In addition, the generated ROS promotes the decomposition of the surface‐tethered LA, enabling the controlled release of nitric oxide (NO) gas at the tumor site, thereby achieving a combination therapeutic effect. In vivo experiments exhibit remarkable tumor suppression rate (89.5%) in 4T1 tumor mice model, demonstrating the effectiveness of this strategy. The ion doping and oxygen vacancy engineering to improve sonosensitizers, along with the synergistic combination of sonodynamic and gas therapy, provides promising avenues for improving cancer therapy. [ABSTRACT FROM AUTHOR]

The development of thin-film thermoelectric generators for micro-energy harvesting is highly anticipated. In this study, we have investigated the synthesis and thermoelectric applications of ternary alloy InAs1−xSbx thin films, which are narrow-gap III–V compound semiconductors. Polycrystalline InAs1−xSbx thin films with sub-micrometer grain size were synthesized on glass using molecular-beam deposition at 400 °C with all composition x. The InAs1−xSbx thin films exhibited n-type conduction, and their electrical and thermoelectric properties were strongly dependent on x and the amount of Sn doping. The ternary alloying reduced the power factor and contributed to a reduction in thermal conductivity. The InAs0.2Sb0.8 thin film on a glass substrate exhibited a power factor of 100 μW m−1 K−2 and a thermal conductivity of 2.0 W m−1 K−1 at room temperature. Furthermore, a comparable performance was demonstrated for an InAs0.2Sb0.8 thin film grown on a plastic film. These achievements will pave the way for the application of III–V compound semiconductors in flexible thermoelectric generators. [ABSTRACT FROM AUTHOR]

Various types of magnetism can appear in emerging quantum materials such as van der Waals layered ones. Here, we report the successful doping of manganese atoms into a post-transition metal dichalcogenide semiconductor: SnSe2. We synthesized a single crystal Sn1−xMnxSe2 with x = 0.04 by the chemical vapor transport method and characterized it by x-ray diffraction and energy-dispersive x-ray spectroscopy. The magnetic properties indicated a competition between coexisting ferromagnetic and antiferromagnetic interactions, from the temperature dependence of the magnetization, together with magnetic hysteresis loops. This means that magnetic clusters having ferromagnetic interactions within a cluster form and the short-range antiferromagnetic interaction works between the clusters; a spin-glass-like state appears below ∼60 K. Furthermore, we confirmed by ab initio calculations that the ferromagnetic interaction comes from the 3d electrons of the manganese dopant. Our results offer a new material platform to understand and utilize the magnetism in the van der Waals layered materials. [ABSTRACT FROM AUTHOR]

Various types of magnetism can appear in emerging quantum materials such as van der Waals layered ones. Here, we report the successful doping of manganese atoms into a post-transition metal dichalcogenide semiconductor: SnSe2. We synthesized a single crystal Sn1−xMnxSe2 with x = 0.04 by the chemical vapor transport method and characterized it by x-ray diffraction and energy-dispersive x-ray spectroscopy. The magnetic properties indicated a competition between coexisting ferromagnetic and antiferromagnetic interactions, from the temperature dependence of the magnetization, together with magnetic hysteresis loops. This means that magnetic clusters having ferromagnetic interactions within a cluster form and the short-range antiferromagnetic interaction works between the clusters; a spin-glass-like state appears below ∼60 K. Furthermore, we confirmed by ab initio calculations that the ferromagnetic interaction comes from the 3d electrons of the manganese dopant. Our results offer a new material platform to understand and utilize the magnetism in the van der Waals layered materials. [ABSTRACT FROM AUTHOR]

High-temperature ferromagnetism has always been a classic and interesting subject, especially in spin gapless semiconductor PbPdO 2 with exotic properties. Here, a combination of theoretical and experimental studies was employed to clarify the origin of high Tc. First, based on first-principles calculations, electronic band structures of PbPd 0.875 Co 0.125 O 2 at different Co substitution positions were studied. Our results indicate that Co atoms tend to form an antiferromagnetic ground state due to the Co–O–Co (180 °) indirect exchange effect, while ferromagnetism is favored in Co-doped PbPdO 2 when a unique molecular field effect induced band crossover and p – d coupling occurs. It is revealed that metallic or semiconductor properties have an important connection with ferromagnetism or antiferromagnetism. Subsequently, a Monte Carlo simulation was carried out based on the first-principles results to predict the ferromagnetism of PbPd 0.875 Co 0.125 O 2. Finally, the moment-magnetic field and moment-temperature curves were also measured for PbPd 0.875 Co 0.125 O 2 samples, which was found well consistent with the theoretical findings. The ground state of PbPd 0.875 Co 0.125 O 2 was confirmed to be ferromagnetic. Our results well explain the origin of high-temperature ferromagnetism in diluted magnetic semiconductors and provide new approaches for the design of future high Tc spintronic devices. [ABSTRACT FROM AUTHOR]

Occurrence of unintended gas breakdown in the narrow gaps of plasma processing chambers is one of the critical challenges in developing advanced plasma sources. We present a combined experimental and theoretical study of unintended discharges in the narrow gaps of plasma processing chambers and report significant drop of the gas breakdown voltage in the presence of a background plasma facing the gap. Experimentally measured breakdown voltages decrease in subsequent breakdown events due to wall erosion caused by the discharge. Therefore, preventing and mitigating the first discharge is of paramount importance. An analysis of kinetic simulation results indicates that the charged particle influx from the background plasma in the processing chamber into the gap is responsible for the onset of early breakdown: higher charged particle density within the gap modifies the electric field profile, allowing unintended breakdowns to occur at a significantly reduced threshold voltage. [ABSTRACT FROM AUTHOR]

PdSe2, a semiconductor with a narrow band gap, shows tremendous promise for high‐performance broadband photodetectors. In this study, highly sensitive, broadband, and flexible PdSe2 thin film photodetectors on polyimide (PI) substrates that can detect light from the UV (365 nm) to infrared (2200 nm) regions are reported. The devices with thick (21 nm) PdSe2 films show decent performance with a decent responsivity of 37.6 mA W−1 at 1550 nm and a fast response time. For the thick PdSe2 film, the bolometric effect dominates the positive photoresponse across all wavelength regions, whereas for the thin PdSe2 film (4.5–13 nm), which shows both positive and negative photoresponses, it dominates in the infrared region. The negative photoresponse of thin PdSe2 in the UV to the VIS region is attributed to the charge transfer‐related adsorption‐desorption of gas molecules. Detailed investigations revealed that the temperature coefficient of resistance (TCR) value is closely correlated to film thickness, with the thinnest film exhibiting the highest absolute TCR value of up to 4.3% °C−1. The value is much larger than that of metals, most 2D materials, amorphous Si, and even commercial VOx. These findings suggest that PdSe2 films have a promising future in broadband photodetectors. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) water splitting for hydrogen production technology is considered as one of the most promising solutions to energy shortage and environmental remediation. TiO2/NiS nanorod arrays were successfully prepared using hydrothermal deposition followed by the successive ionic layer adsorption and reaction (SILAR) method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and photoluminescence (PL) spectra characterization studies indicate the successful deposition of NiS on TiO2 NRs. The NiS deposition on TiO2 was optimized by controlling the impregnation cycle. The optimal sample exhibits a photocurrent density of 1.16 mA cm−2 at 0.6 V vs. Ag/AgCl, which is a 1.9-fold enhancement over that of pristine TiO2 nanorod arrays. The enhanced photoelectrochemical performance can be attributed to two aspects. On the one hand, the (101) crystal plane of rutile TiO2 is the facet where photogenerated holes accumulate and is an efficient active plane for the oxygen evolution reaction; on the other hand, NiS is a narrow band gap semiconductor, and its deposition on TiO2 nanorods can further promote the separation and transport of photogenerated charge carriers. [ABSTRACT FROM AUTHOR]

The discovery of topological insulators and semimetals triggered enormous interest in exploring emergent electromagnetic responses in solids. Particular attention has been focused on ternary half-Heusler compounds, whose electronic structure bears analogy to the topological zinc-blende compounds while also including magnetic rare-earth ions coupled to conduction electrons. However, most of the research in this system has been in band-inverted zero-gap semiconductors such as GdPtBi, which still does not fully exhaust the large potential of this material class. Here, we report a less-studied member of half-Heusler compounds, HoAuSn, which we show is a trivial semimetal or narrow-gap semiconductor at zero magnetic field but undergoes a field-induced transition to a Weyl semimetal, with a negative magnetoresistance exceeding four orders of magnitude at low temperatures. The combined study of Shubnikov-de Haas oscillations and first-principles calculation suggests that the exchange field from Ho 4f moments reconstructs the band structure to induce Weyl points which play a key role in the strong suppression of large-angle carrier scattering. Our findings demonstrate the unique mechanism of colossal negative magnetoresistance and provide pathways towards realizing topological electronic states in a large class of magnetic half-Heusler compounds. Half-Heusler alloys containing rare earth ions have attracted interest due to combination of band-inversion and magnetism. Ueda et al study less studied trivial semiconductor HoAuSn, and show that it undergoes a magnetic field induced transition to a Weyl semimetal state, with a large reduction in the resistance. [ABSTRACT FROM AUTHOR]

Combining the strategies of introducing larger heteroatom, regio-regular backbone and extended branching position of side-chain, we developed polymer semiconductors (PPCPD) with narrow band-gap to construct the photosensing layer of thin-film photodiodes and image arrays. The spectral response of the resulting organic photodiodes spans from the near ultra-violet to short-wavelength infrared region. The performance of these short-wavelength infrared photodiodes in 900–1200 nm range achieved a level competitive with that of indium gallium arsenide-based inorganic crystalline detectors, exhibiting a specific detectivity of 5.55×1012 Jones at 1.15 µm. High photodetectivity and quantum efficiency in photodiode with amorphous/nanocrystalline thin-films of 100–200 nm thickness enabled high pixel-density image arrays without pixel-level-patterning in the sensing layer. 1 × 256 linear diode arrays with 25 µm × 25 µm pixel pitch were achieved, enabling high pixel-density short-wavelength infrared imaging at room temperature. [ABSTRACT FROM AUTHOR]

We present a brief review of experimental and theoretical papers on studies of electron transport and magnetic properties in manganese-based compounds Mn2YZ and Mn3Z (Y = V, Cr, Fe, Co, Ni, etc.; Z = Al, Ge, Sn, Si, Pt, etc.). It has been shown that in the electronic subsystem of Mn2YZ compounds, the states of a half-metallic ferromagnet and a spin gapless semiconductor can arise with the realization of various magnetic states, such as a ferromagnet, a compensated ferrimagnet, and a frustrated antiferromagnet. Binary compounds of Mn3Z have the properties of a half-metallic ferromagnet and a topological semimetal with a large anomalous Hall effect, spin Hall effect, spin Nernst effect, and thermal Hall effect. Their magnetic states are also very diverse: from a ferrimagnet and an antiferromagnet to a compensated ferrimagnet and a frustrated antiferromagnet, as well as an antiferromagnet with a kagome-type lattice. It has been demonstrated that the electronic and magnetic properties of such materials are very sensitive to external influences (temperature, magnetic field, external pressure), as well as the processing method (cast, rapidly quenched, nanostructured, etc.). Knowledge of the regularities in the behavior of the electronic and magnetic characteristics of Mn2YAl and Mn3Z compounds can be used for applications in micro- and nanoelectronics and spintronics. [ABSTRACT FROM AUTHOR]

Solid-state thermoelectric devices offer the possibility of exploiting waste heat from engines and power plants and converting it into electrical energy. One of the greatest challenges in the development of thermoelectric material systems is to find new thermoelectric materials with high thermoelectric figures of merit ZT. In this work, the structural, electronic and thermoelectric properties of PbSe 1 − x S x (x = 0 , 0.25, 0.50, 0.75 and 1) semiconductors are investigated by applying density functional theory in a full potential linearized augmented plane wave method (FP-LAPW). Calculations of structural properties were completed using the generalized gradient approximation GGA of Perdew Burke and Ernzerhof PBE to get reliable lattice constant results with experimental values. The obtained electronic results show that the PbSe 1 − x S x material is a narrow band gap semiconductor. In addition, the thermoelectric properties are studied on the basis of the fully iterative solution of the Boltzmann transport equation. PbSe 1 − x S x had a high figure of merit indicating that our materials are promising candidates in thermoelectric applications. [ABSTRACT FROM AUTHOR]

Magnetotransport and thermal properties of microwave-synthesized nanostructured Bi2Te3, a well-known material of topological interest, have been studied in detail. Temperature-dependent resistivity shows a disordered metal-like behavior at high temperature with unsaturated ln(T)-dependent upturns at low temperature manifesting localization tendency. The slopes (κ) of the normalized conductivity (Δσ) vs ln(T) curves change sharply with magnetic fields upto 1 T and then saturate at a certain higher field (Bϕ), which is an indication of a combined electron–electron interaction and quantum interference effect (QIE) dominated transport. A noteworthy result is a crossover from positive to negative Coulomb screening factor (F) in Bi2Te3. Low-field (H ≤ 1 T) magnetoconductivity at low temperature follows a 2D Hikami–Larkin–Nagaoka equation, thereby revealing the QIE and associated dephasing nature of the electronic states at high temperatures. High-field (14 T) magnetoresistance (MR) at 2 K shows interesting features like low-field weak antilocalization, possibly a defect-induced negative MR that vanishes after post-annealing treatment, and a high field parabolic character in place. The Seebeck coefficient (S) is negative and varies quasilinearly with a slight but notable slope change at intermediate temperatures. Heat capacity measurements are in line with a narrow gap degenerate semiconductor with a low θD of 140 K. A combined analysis of heat capacity and thermopower reveals the localization of carriers at low temperatures and is in line with transport data. [ABSTRACT FROM AUTHOR]

Spin-gapless semiconductors (SGSs) are new states of quantum matter, which are characterized by a unique spin-polarized band structure. Unlike conventional semiconductors or half-metallic ferromagnets, they carry a finite bandgap for one spin channel and a close (zero) gap for the other and thus are useful for tunable spin transport applications. It is one of the latest classes of materials considered for spintronic devices. A few of the several advantages of SGS include (i) a high Curie temperature, (ii) a minimal amount of energy required to excite electrons from the valence to conduction band due to zero gap, and (iii) the availability of both charge carriers, i.e., electrons as well as holes, which can be 100% spin-polarized simultaneously. In this perspective article, the theoretical foundation of SGS is first reviewed followed by experimental advancements on various realistic materials. The first band structure of SGS was reported in bulk Co-doped PbPdO 2 , using first-principles calculations. This was followed by a large number of ab initio simulation reports predicting SGS nature in different Heusler alloy systems. The first experimental realization of SGS was made in 2013 in a bulk inverse Heusler alloy, Mn 2 CoAl. In terms of material properties, SGS shows a few unique features such as nearly temperature-independent conductivity (σ) and carrier concentration, a very low temperature coefficient of resistivity, a vanishingly small Seebeck coefficient, quantum linear magnetoresistance in a low temperature range, etc. Later, several other systems, including 2-dimensional materials, were reported to show the signature of SGS. There are some variants of SGSs that can show a quantum anomalous Hall effect. These SGSs are classic examples of topological (Chern) insulators. In the later part of this article, we have touched upon some of these aspects of SGS or the so-called Dirac SGS systems as well. In general, SGSs can be categorized into four different types depending on how various bands corresponding to two different spin channels touch the Fermi level. The hunt for these different types of SGS materials is growing very fast. Some of the recent progress along this direction is also discussed. [ABSTRACT FROM AUTHOR]

The electronic and charge transport properties of porphyrin and tetra-indole porphyrinoid single layer covalent organic frameworks (COFs) are investigated by means of density functional theory calculations. Ultrathin diacetylene-linked COFs based on oxidized tetra-indole cores are narrow gap 2D semiconductors, featuring a pronounced anisotropic electronic band structure due to the combination of dispersive and flat band characteristics, while registering high room temperature charge carrier mobilities. The capability of bandgap and charge carrier localization tuning via the careful selection of fourfold porphyrin and porphyrinoid cores and twofold articulated linkers is demonstrated, with the majority of systems exhibiting electronic gap values between 1.75 eV and 2.3 eV. Tetra-indoles are also capable of forming stable monolayers via non-articulated core fusing, resulting in 2D morphologies with extended π-conjugation and semi-metallic behavior. [ABSTRACT FROM AUTHOR]

The structural, electronic, elastic, lattice dynamical properties and pressure-induced phase transitions in ThN2, Th2N3, and Th3N4 have been investigated through density functional theory based electronic band structure calculations. Our theoretical calculations on ThN2 reveal the monoclinic structure (C2/m space group) at 0 GPa instead of the previously reported cubic (Fm 3 ¯ m spatial crystal symmetry) phase [K. O. Obodo and N. Chetty, J. Nucl. Mater. 440, 229 (2013)]. More refined calculations on enthalpy of formation reveal that this ground state C2/m phase of ThN2 transforms to an orthorhombic structure (Pnma symmetry) at a pressure of ∼7 GPa. In agreement with experimental observations, we predict the La2O3-type trigonal structure (P 3 ¯ ml symmetry) in Th2N3 at ambient conditions, which is further predicted to transform to an initial monoclinic structure again at ∼62 GPa. Our theoretical results also agree with the experiment regarding the rhombohedral structure (R 3 ¯ m symmetry) of Th3N4 revealed at 0 GPa, which, at ∼37 GPa, is predicted to transform to an another rhombohedral structure with reduced space group symmetry of R 3 ¯ . The predicted structural phases are further substantiated with the mechanical and dynamical stability criteria in the pressure regime of their structural stability. Furthermore, the electronic band structure calculations at zero pressure suggest that with limited density of states above Fermi energy, ThN2 and Th2N3 exhibit semi-metallic characteristics, whereas a bandgap of ∼1.44 eV in Th3N4 makes it a semiconductor. The semiconducting nature of Th3N4 ceases at a transition pressure of ∼62 GPa. [ABSTRACT FROM AUTHOR]

We consider two cobalt-based full-Heusler compounds, CoFeTiAl and Co 2 FeSi, for which Coulomb correlation effects play an important role. Since the standard GGA scheme does not provide a precise description of the electronic properties near the Fermi level, we use a meta-GGA functional capable to improve the description of the electronic properties of CoFeTiAl and Co 2 FeSi. In particular, we find a better agreement with the experiment for the magnetic moment and the energy bandgap. Moreover, our calculations show that pressure enhances the insulating properties of Co 2 FeSi and CoTiFeAl. [ABSTRACT FROM AUTHOR]

This paper studies the dependence of the specific heat capacity (Cp) of activated carbon obtained by the activation of coke fines on temperature (T, K) and the dependence of electrical resistance (R, Om) on temperature (T, K). In the course of the work, it was found that in the temperature range of 298.15–448 K on the curve of dependence Cp − f(T) at 323 K there is a jump in heat capacity, associated with a phase transition of the second kind. Measurements of the temperature dependence of electrical resistance on temperature were also carried out, which showed that activated carbon in the temperature range of 293–343 K exhibits metallic conductivity, turning into a semiconductor in the temperature range of 343–463 K. The calculation of the band gap showed that the resulting activated carbon is a semiconductor with a moderately narrow band gap. The satisfactory agreement of the phase transition temperatures on the curves of the temperature dependences of the heat capacity on temperature (323 K) and on the curves of the dependences of electrical resistance and the relative permittivity on temperature (343 K) indicates the nature of this phase transition, i.e., at a temperature of 323 K, the change in heat capacity is associated with the transition from semiconductor conductivity to metallic. [ABSTRACT FROM AUTHOR]

The results of experimental studies of magnetoresistance oscillations are described for a HgSe monocrystal with Co impurities of low concentration (<1 at %). It has been discovered that at such impurity concentrations (∼1018 cm–3) there exists two types of magnetic oscillations: Shubnikov de Haas oscillations at low temperatures (T < 10 K) and magnetophonon oscillations at higher temperatures (T > 10 K). The first ones are caused by the interaction of electrons with magnetic field inside of a Landau sublevel and the latter—by the interaction with longitudinal optical phonons. The differences of these oscillations are characterized. A hypothesis of a nature of magnetophonon oscillations in such structures is proposed. [ABSTRACT FROM AUTHOR]

Using the first-principle simulations and the Boltzmann transport equation, our study investigated the properties of single-layer SnBi 2 Se 4 and PbBi 2 Se 4 , including stability, elasticity, electronic and thermoelectric transport properties. We discovered that both 2D materials have acceptable cleavage energies ranging from 0.27 to 0.28 J/m2 and that they are indirect semiconductors with narrow band gaps of 0.68 eV and 0.94 eV, respectively. Interestingly, the valence band maximum exhibits 'multi-valley' energy dispersion. Furthermore, SnBi 2 Se 4 and PbBi 2 Se 4 have comparable electron and hole mobility of about ∼102 cm2/Vs and ∼103 cm2/Vs, respectively resulting in high conductivity and a high thermoelectric power factor. Owing to low group velocities and strong phonon–phonon scattering rates, the materials exhibit low lattice thermal conductivities of 2.59 W/mK (SnBi2Se 4) and 1.73 W/mK (PbBi 2 Se 4). Thus, they demonstrate high thermoelectric figures of merit, namely 0.31 (SnBi2Se 4) and 0.37 (PbBi 2 Se 4) at 300 K, which rise further to 1.22 and 1.82, respectively, at 700 K. Our results suggest that these two single-layer materials are promising candidates for use in nanoelectronics and thermoelectric appliances. [ABSTRACT FROM AUTHOR]

Because of its superior coupling and composition matching, narrow band gap semiconductor heterojunction can increase redox activity, reduce carrier recombination, and enhance light absorption. When heterojunction photocatalysts are constructed properly, it is thought to be an efficient technique to boost photocatalytic activity. The Co 9 S 8 /CdS heterostructures in this study were created using a two-step solvothermal technique. The as-prepared Co 9 S 8 /CdS heterostructures exhibit outstanding photocatalytic degradation performance of methyl orange (MO) owing to their unique structure and compositional properties. Co 9 S 8 /CdS heterostructures can offer a remarkable MO degradation rate that can reach 97% in 25 min when illuminated by visible light. In addition to demonstrating better long-term stability after numerous cycling photocatalytic tests, experiments with radical trapping have shown that ·O 2 − is crucial for the photocatalytic degradation of MO. The pertinent photogenerated charge transfer and catalytic mechanisms of Co 9 S 8 /CdS heterostructures are suggested and examined. [ABSTRACT FROM AUTHOR]

Spin gapless semiconductor (SGS) presents abundant electric and magnetic properties and is highly sensitive to external factors, such as current, electric field, magnetic field, and stress. This paper reports on a PbPd0.9Co0.1O2/PMNPT(001) laminate thin film with the "SGS/ferroelectrics" structure, which exhibits significant current-induced resistance (I-ER) effect. More importantly, the colossal static electric-field-induced resistance (E-ER) effect in such a laminate film was observed for the first time. The introduction of lattice defects (Pb vacancies) induces a local electric field, electron spin ordering state, and ferroelectric polarization field effect to explain the excellent physical properties. The reported laminate thin film composite exhibits promising application potential in spintronic devices, composite sensor units, storage systems, and other low-energy semiconductor electronic device fields. This work proposes an alternative way to investigate the novel properties for spin gapless semiconductors and expand the research fields of multi-field modulation effect in magnetoelectric composites. [ABSTRACT FROM AUTHOR]