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Solid-state thermomagnetic modules operating based on the Nernst–Ettingshausen effects are an alternative to conventional solid-state thermoelectric modules. These modules are appropriate for low-temperature applications where the thermoelectric modules are not efficient. Here, we briefly discuss the application, performance, similarities, and differences of thermoelectric and thermomagnetic materials and modules. We review thermomagnetic module design, Nernst coefficient measurement techniques, and theoretical advances, emphasizing the Nernst effect and factors influencing its response in semimetals such as carrier compensation, Fermi surface, mobility, phonon drag, and Berry curvature. The main objective is to summarize the materials design criteria to achieve high thermomagnetic performance to accelerate thermomagnetic materials discovery. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides with 2H-phases, as a unique platform of valleytronics, display valley polarization and the well-known anomalous valley Hall effect when stacking with 2D magnetic substrates. In this study, we employ first-principles calculations to investigate the magnetic states, band structures, and magnetic proximity-dependent valley properties of 2D van der Waals heterostructures Cr2Ge2Te6/2H-MX2 (M = Mo, W, and X = S, Se, Te). Our findings reveal that the heterostructures possess stacking-dependent spontaneous valley polarization as well as pristine perpendicular magnetic anisotropy. Additionally, the Berry curvature and circular polarization demonstrate the presence of spin–momentum coupling characteristics, while the calculated non-zero Hall voltage indicates that the anomalous valley Hall effect can be achieved in valley-polarized systems. Furthermore, due to the strain effect and the electronic polarization at the interface, Cr2Ge2Te6/2H-MX2 heterostructures undergo the transition from semiconductors to semimetals upon substitution of early chalcogen elements. These calculations provide valuable insights for practical applications of valleytronics in 2D van der Waals heterostructure systems. [ABSTRACT FROM AUTHOR]

Transition metal catalysts supported on topological insulators are predicted to show improved catalytic properties due to the presence of topological surface states, which may float up to the catalysts and provide robust electron transfer. However, experimental studies of surface structures and corresponding catalytic properties of transition metal/topological insulator heterostructures have not been demonstrated so far. Here, we report the structures, chemical states, and adsorption behaviors of two conventional transition metal catalysts, Pt and Pd, on the surface of Bi2Se3, a common topological insulator material. We reveal that Pt forms nanoparticles on the Bi2Se3 surface. Moreover, the interaction between Pt and surface Se is observed. Furthermore, thermal dosing of O2 onto the Pt/Bi2Se3 heterostructure leads to no oxygen adsorption. Detailed scanning tunneling microscopy study indicates that Pt transforms into PtSe2 after the thermal process, thus preventing O2 from adsorption. For another transition metal Pd, it exhibits approximate layer-island growth on Bi2Se3, and Pd–Se interaction is also observed. Our work provides significant insights into the behaviors of transition metals on top of a common topological insulator material and will assist in the future design of catalysts built with topological materials. [ABSTRACT FROM AUTHOR]

The binary high-pressure phase diagram of the Ta–Sb system was constructed for the first time in this study, utilizing the evolutionary algorithm USPEX and density functional theory (DFT). Ten pressurized dynamically and mechanically stable or metastable novel phases of Ta–Sb were discovered, including I4/mmm-TaSb2, P4/nmm-TaSb, P-3-Ta2Sb7, I4/mmm-Ta2Sb3, P-4m2-Ta7Sb, Pm-3-Ta7Sb, Pmm2-Ta15Sb, P4/nmm-TaSb3, I4/mmm-Ta3Sb4, and I4/mmm-Ta2Sb5. The compounds P-4m2-Ta7Sb and Pmm2-Ta15Sb exhibit promising characteristics as non-centrosymmetric superconductors (NCSs), with their superconducting critical temperature (TC) being 3.831 and 3.221 K, respectively. The application of pressure tuning is predicted to transform the topological characteristics of P4/nmm-TaSb, causing it to transition from a topological insulator state to a Dirac semimetal state and ultimately reverting back to a topological insulator state. Therefore, the P4/nmm-TaSb compound is considered a promising candidate to investigate topological and superconducting excitations. Moreover, the mechanical and thermal properties of Ta–Sb binary phases were also investigated. The thermal conductivity of I4/mmm-TaSb2, P4/nmm-TaSb, and P4/nmm-TaSb3 all surpasses 20 W m−1 K−1 at 1000 K, showcasing their excellent thermal conductivity properties. The present study addresses the research gap concerning high-pressure structures in the Ta–Sb binary system, thereby offering valuable insights for the design and development of intermetallic compounds within this binary system. [ABSTRACT FROM AUTHOR]

Transition metal catalysts supported on topological insulators are predicted to show improved catalytic properties due to the presence of topological surface states, which may float up to the catalysts and provide robust electron transfer. However, experimental studies of surface structures and corresponding catalytic properties of transition metal/topological insulator heterostructures have not been demonstrated so far. Here, we report the structures, chemical states, and adsorption behaviors of two conventional transition metal catalysts, Pt and Pd, on the surface of Bi2Se3, a common topological insulator material. We reveal that Pt forms nanoparticles on the Bi2Se3 surface. Moreover, the interaction between Pt and surface Se is observed. Furthermore, thermal dosing of O2 onto the Pt/Bi2Se3 heterostructure leads to no oxygen adsorption. Detailed scanning tunneling microscopy study indicates that Pt transforms into PtSe2 after the thermal process, thus preventing O2 from adsorption. For another transition metal Pd, it exhibits approximate layer-island growth on Bi2Se3, and Pd–Se interaction is also observed. Our work provides significant insights into the behaviors of transition metals on top of a common topological insulator material and will assist in the future design of catalysts built with topological materials. [ABSTRACT FROM AUTHOR]

With the in-depth study of open optical systems, the topological phases of non-Hermitian metasurfaces have attracted increasing attention due to their topological protection properties. Here, in this paper, a tunable non-Hermitian metasurface with bidirectional anisotropism is proposed. By incorporating the phase change material vanadium dioxide (VO2) into the metasurface, two topological exceptional points (EPs) appear in the system by adjusting the conductivity of VO2 and chiral responses appear at both EPs. This research shows that the conductivity significantly affects the reflection of the metasurface, and the zero-reflection points correspond to the EPs of the non-Hermitian system. Further results prove that circling around EPs leads to a 2π phase change, which is topologically protected and independent of the encirclement path. Therefore, this study employs an active control approach to realize two topological EPs. Through comprehensive investigations into the topological properties and chiral performance at EPs, we elucidate the mechanism for the chirality generation in non-Hermitian metasurfaces, which offers feasible solutions for the development of chiral topological devices and light transmission and modulation in future applications. [ABSTRACT FROM AUTHOR]

MnBi2Te4 can generate a variety of exotic topological quantum states, which are closely related to its special structure. We conduct comprehensive multiple-cycle high-pressure research on MnBi2Te4 by using a diamond anvil cell to study its phase transition behaviors under high pressure. As observed, when the pressure does not exceed 15 GPa, the material undergoes an irreversible metal–semiconductor–metal transition, whereas when the pressure exceeds 17 GPa, the layered structure is damaged and becomes irreversibly amorphous due to the lattice distortion caused by compression, but it is not completely amorphous, which presents some nano-sized grains after decompression. Our investigation vividly reveals the phase transition behaviors of MnBi2Te4 under high pressure cycling and paves the experimental way to find topological phases under high pressure. [ABSTRACT FROM AUTHOR]

MnBi2Te4 can generate a variety of exotic topological quantum states, which are closely related to its special structure. We conduct comprehensive multiple-cycle high-pressure research on MnBi2Te4 by using a diamond anvil cell to study its phase transition behaviors under high pressure. As observed, when the pressure does not exceed 15 GPa, the material undergoes an irreversible metal–semiconductor–metal transition, whereas when the pressure exceeds 17 GPa, the layered structure is damaged and becomes irreversibly amorphous due to the lattice distortion caused by compression, but it is not completely amorphous, which presents some nano-sized grains after decompression. Our investigation vividly reveals the phase transition behaviors of MnBi2Te4 under high pressure cycling and paves the experimental way to find topological phases under high pressure. [ABSTRACT FROM AUTHOR]

Development of nanophotonics has made it possible to control the wavelength and direction of thermal radiation emission, but it is still limited by Kirchhoff's law. Magneto-optical materials or Weyl semimetals have been used in recent studies to break the time-reversal symmetry, resulting in a violation of Kirchhoff's law. Currently, most of the work relies on the traditional optical design basis and can only realize the nonreciprocal thermal radiation at a specific angle or wavelength. In this work, on the basis of material informatics, a design framework of a multilayer nonreciprocal thermal absorber with high absorptivity and low emissivity at any arbitrary wavelength and angle is proposed. Through a comprehensive investigation of the underlying mechanism, it has been discovered that the nonreciprocal thermal radiation effect is primarily attributed to excitation of the cavity mode at the interface between the metal and the multilayer structure. Moreover, the impact of factors, such as layer count, incidence angle, extinction coefficient, and applied magnetic field on nonreciprocal thermal radiation, is thoroughly explored, offering valuable insights to instruct the design process. Additionally, by expanding the optimization objective, it becomes feasible to design fixed dual-band or even multi-band nonreciprocal thermal absorbers. Consequently, this study offers essential guidelines for advancing the control of nonreciprocal thermal radiation. [ABSTRACT FROM AUTHOR]

In the present study, we have explored the absorption properties of a monolayer graphene-based photonic heterostructure, which consists of topological photonic configurations, graphene, and a Bragg mirror. The optical attributes were computed by using the 4 × 4 transfer matrix method. The results indicate that the creation of topological interface states and strong coupling between these resonant modes result in mode splitting, leading to the formation of hybrid modes known as coupled topological interface states with unity transmittance. The number of absorption modes can be modulated with an appropriate selection of cascaded photonic structures. Our proposed design with 1, 3, 5, and 7 cascaded topological photonic structures provides 1, 5, 9, and 13 absorption modes with greater than 90 % absorption. The findings also reveal that absorption peak strength is greatly influenced by Fermi-level and magnetic fields; switching of the modes from absorption to reflection and vice versa is achieved by suitable electrical and magnetic biasing. Our proposed design offers various applications, such as switchable filters, absorbers, and modulators. [ABSTRACT FROM AUTHOR]

Low-dimensional materials with topologically protected edge states have wide applications in spintronic, valleytronic, and optoelectronic nanodevices. Different from the valley-resolved quantum anomalous Hall (VQAH) state and spin-polarized quantum anomalous Hall (VSQAH), the photon-induced topological states in kagome-lattice nanoribbons (KLNR) can generate both valley and spin-polarized edge states without magnetic substrate or Rashba spin-orbit coupling (SOC). Via the Floquet theory, we also propose a 0-photon-extraction scheme to obtain the effective Hamiltonian under low-frequency light for the first time, and we analyze the topological properties and phase transition of the irradiated kagome system, similar with those in the high-frequency case. We then design an all-optically controlled valley-resolved spin filter based on KLNR. Transmissions and local current distributions of the proposed nanodevice confirm this spin-filter effect, which can indeed be switched by left- or right-circularly-polarized (LCP/RCP) light. We believe these optically controlled models can be extended to the design of magnetism-free spin-valley filter or switcher in the future. [ABSTRACT FROM AUTHOR]

Specific properties, such as surface Fermi arcs, features of quantum oscillations and of various responses to a magnetic field, distinguish Dirac semimetals from ordinary materials. These properties are determined by Dirac points at which a contact of two electron-energy bands occurs and in the vicinity of which these bands disperse linearly in the quasimomentum. This work shows that almost the same properties are inherent in a wider class of materials in which the Dirac spectrum can have a noticeable gap comparable with the Fermi energy. In other words, the degeneracy of the bands at the point and their linear dispersion are not necessary for the existence of these properties. The only sufficient condition is the following: In the vicinity of such a quasi-Dirac point, the two close bands are well described by a two-band model that takes into account the strong spin-orbit interaction. To illustrate the results, the spectrum of ZrTe5 is considered. This spectrum contains a special quasi-Dirac point, similar to that in bismuth. Dirac semimetals are 3D materials where the conduction and valence bands meet at what are called Dirac points. The author shows that almost all the properties inherent in the Dirac semimetals are exhibited by a wider class of materials that need not have the gapless Dirac points. [ABSTRACT FROM AUTHOR]

The investigations of polar topological conformations have become one of the hotspots due to their multitudinous physical properties and potential applications in emerging electronic devices. However, constructing polar topologies in bulk form is exceedingly challenging. In this study, bubble domains with different polar topologies, including flux-closure and half-closure, are successfully achieved in Cu-doped (K,Na)(Nb,Ta)O 3 single crystals by elaborately adjusting the phase structure and defect dipoles. The coexistence of orthorhombic and tetragonal phases results in a flattened free energy landscape, while the presence of a high concentration of defect dipoles in local regions leads to the generation of the strong internal electric field, further modifying the energy profile. The interplay of various types of energies gives rise to the smooth rotation of the polar vectors, facilitating the formation of topological structures. These findings provide a practical method for constructing topological bubble domains in bulk materials, thereby enriching the understanding of the physical properties arising from topological structures. [ABSTRACT FROM AUTHOR]

Trace metals and metalloids are groups of chemical elements that naturally occur in low concentrations and cycle in the environment driven by natural processes and human activities. They have a persistent and bio-accumulative tendency in the environment, and certain trace metals and metalloids have become a public health concern. This study assesses the concentration of eleven trace metals and a metalloid in sediments and catfish muscle from five study sites in the Eastern Tanzanian River basin. Forty catfish tissues and fifteen sediment samples were collected and analyzed using ICP-MS. Concentrations of As, Cd, Co, Pb, and Zn did not exceed the United States Environmental Protection Agency (USEPA) guideline for pollution of sediments, while Al Cr, Al, Mn, and V with values ranging from (118.54 to 70154.55) indicating moderately polluted. The stations Java-Sadaani and Matandu showed the highest Cr, Ni, and Cu concentrations, but the potential ecological risk index (RI) was low (RI < 95). In the catfish muscle tissue, the levels of Cd, Pb, Cu, and Zn did not surpass the EU and FAO/WHO limits and results ranged from 2.22 to 35.22mg/kg. Low levels of accumulation of Cd, Pb, and As were found in this study compared to catfish muscles from other studies, whereas the concentrations of other trace metals and metalloids analyzed had comparable results. Biota/sediment accumulation factors (BSAF) were all < 1. The weekly metal intake (MWI) results ranged from 6.89E-04 to 2.43E+01 μg/know-1week-1, indicating a low risk as the value did not exceed the FAO/WHO established Permissible Tolerable Weekly Intake (PTWI). The non-carcinogenic health risk result THQ was 4.43E-02 and the carcinogenic health risks result HI was 4.42E-05 which indicated tolerable levels of risks as both the values of the Target Hazard Quotient (THQ) and the Hazard Index (HI) was < 1, and the carcinogenic target risk (TR) is < 0.0001. The highest TR values were observed for Cr and Ni. We recommend a continued monitoring of the changes in trace metal levels in the environment and biota together with continuous public health education on the dangers of high levels of trace metals. [ABSTRACT FROM AUTHOR]

Heusler compounds belong to a large family of materials and exhibit numerous physical phenomena with promising applications, particularly ferromagnetic Weyl semimetals for their use in spintronics and memory devices. Here, anomalous Hall transport is reported in the room‐temperature ferromagnets NiMnSb (half‐metal with a Curie temperature (TC) of 660 K) and PtMnSb (pseudo half‐metal with a TC of 560 K). They exhibit 4 µB/f.u. magnetic moments and non‐trivial topological states. Moreover, NiMnSb and PtMnSb are the first half‐Heusler ferromagnets to be reported as Weyl semimetals, and they exhibit anomalous Hall conductivity (AHC) due to the extended tail of the Berry curvature in these systems. The experimentally measured AHC values at 2 K are 1.8 × 102 Ω−1 cm−1 for NiMnSb and 2.2 × 103 Ω−1 cm−1 for PtMnSb. The comparatively large value between them can be explained in terms of the spin‐orbit coupling strength. The combined approach of using ab initio calculations and a simple model shows that the Weyl nodes located far from the Fermi energy act as the driving mechanism for the intrinsic AHC. This contribution of topological features at higher energies can be generalized. [ABSTRACT FROM AUTHOR]

The estrogen receptor alpha (ERa) plays a central role in the etiology, progression, and treatment of breast cancers. Constitutively activating somatic mutations Y537S and D538G, in the ligand binding domain (LBD) of ESR1, are associated with acquired resistance to endocrine therapies. We have previously shown that the metalloestrogen calcium activates ERa through an interaction with the LBD of the receptor. This study shows that cadmium activates ERa through a mechanism similar to calcium and contributes to, and further increases, the constitutive activity of the ERa mutants Y537S and D538G. Mutational analysis identified C381, N532A, H516A/N519A/E523A, and E542/ D545A on the solvent accessible surface of the LBD as possible calcium/metal interaction sites. In contrast to estradiol, which did not increase the activity of the Y537S and D538G mutants, cadmium increased the activity of the constitutive mutants. Mutation of the calcium/metal interaction sites in Y537S and D538G mutants resulted in a significant decrease in constitutive activity and cadmium induced activity. Mutation of calcium/metal interaction sites in wtERa diminished binding of the receptor to the enhancer of estrogen responsive genes and the binding of nuclear receptor coactivator 1 and RNA polymerase II. In contrast to wtERa, mutation of the calcium/metal interaction sites in the Y537S and D538G mutants did not diminish binding to DNA but prevented a stable interaction with the coactivator and polymerase. Growth assays further revealed that calcium channel blockers and chelators significantly decreased the growth of MCF7 cells expressing these constitutively active mutants. Taken together, the results suggest that exposure to cadmium plays a role in the etiology, progression, and response to treatment of breast cancer due, in part, to its ability to activate ERa. [ABSTRACT FROM AUTHOR]

The recent discovery of anti‐chiral edge states in magnetic semimetals linking two unequal‐frequency bulk Dirac nodes manifests a paradoxical picture in contrast to the chiral behavior in Chern insulators, implying an untapped phase may exist. Here, a unique Chern metal, exhibiting a nontrivial Chern number but without a complete bandgap is proposed, and the complete topological phase diagram in the modified Haldane model is obtained. Subsequently, the Chern metal in a 2D honeycomb‐lattice gyromagnetic photonic crystal by simultaneously breaking parity and time‐reversal symmetries with opposite and unequal magnetic biases at different sublattices is realized. For the paired complementary‐shape boundaries, such as zigzag/bearded, it is experimentally revealed that either clockwise or counter‐clockwise chiral character is switchable in Chern metals relying on different boundary choices, a remarkable property deemed as bi‐chiral edge propagation. The topological Chern metal with hidden bulk‐boundary correspondence is articulated to bridge the chiral and anti‐chiral paradox gap between Chern insulators and magnetic semimetals. These results enrich the family of Chern materials and highlight the previously untapped on‐demand control of topological edge states. [ABSTRACT FROM AUTHOR]

Light-rare-earth-based RAlSi family serves as an exceptional platform for elucidating the unique properties of Weyl systems, featuring both types of Weyl fermions, with and without magnetism. In this investigation, we conducted a comparative analysis of the resistivity and magnetoresistance (MR) behaviors of single-crystal RAlSi (R = La, Ce, and Pr). A hump appears in the temperature-dependent resistivity curve of CeAlSi, attributed to the crystal-electric-field effect and showing insensitivity to the magnetic field. In nonmagnetic LaAlSi, a quasilinear MR response above the crossover field is linked to mobility fluctuations originating from slight inhomogeneity. Upon heating CeAlSi from 2 K to its critical temperature for ferromagnetic (FM) ordering (TC), a field-induced contraction in the twin Fermi surfaces was observed, likely contributing to negative MR peaks at TC. The robustness of Weyl nodes in FM RAlSi is demonstrated by the inherent broken space inversion symmetry, allowing them to change positions via violation of time-reversal symmetry. Our findings suggest the potential for magnetic modulation of the electronic structure in FM RAlSi, leading not only to shifts in Weyl nodes but also alterations in the Fermi surface. [ABSTRACT FROM AUTHOR]

Radionuclides and heavy metals/metalloids content in soils and shore sediments of Al-Negila area (Matrouh, Egypt) were determined to assess the associated environmental risks. A total of 46 soil and shore sediment samples were collected and analysed for natural and man-made radionuclides (238U series, 232Th series, 40K and 137Cs) and heavy metals/metalloids (Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mn, Ni, Si, Sr, Zn, and Hg). Within the study area, the soil and shore sediments are mainly calcareous with sandy, sandy clay and silty clay sized textures. The radionuclides and metals/metalloids concentrations in the soil were higher than those in the shore sediments, meanwhile, they are within the safe world average values. The estimated average (±SD) activity concentrations of 226Ra, 228Ra, 40K and 137Cs were 20.3 ± 5.3, 17.8 ± 6.3, 353.1 ± 129.8, and 2.7 ± 2.7 Bq/kg, respectively. The activity concentration of 137Cs is characterised by the greatest variability characterising the fallout deposited radionuclides. The estimated average values of Raeq (72.9 ± 23.7 Bq/kg), air absorbed gamma dose rate (34.9 ± 11.4 nGy/h), annual effective dose (42.8 ± 14.0 µSv/y), and external hazard index (0.2 ± 0.1) are lower than the international averages reported by UNSCEAR 2008. The average concentrations (mg/kg) of heavy metals/metalloids in soil samples decrease in the following order: Mn (129.8) > Sr (95.0) > Si (28.8) > Ba (25.7) > Zn (25.1) > Cr (17.6) > B (10.0) > Ni (3.9) > Cu (3.3) > Co (0.5) > Cd (0.007) > Hg (7.0 µg/kg). According to the classes of pollution load and contamination degree indices, soils and shore sediments of Al-Negila area are generally uncontaminated. However, a few sampling sites were considered moderately contaminated with B, Cd, and Sr. The radionuclides and heavy metal/metalloid contents in the soil and shore sediments of the area should be observed and assessed regularly, especially for 137Cs. [ABSTRACT FROM AUTHOR]

Two-dimensional topological semimetals are typically characterized by the vorticity of gapless points, and can be classified according to the band representations. However, the topological properties involving the distribution of the Berry curvature in the entire Brillouin zone are often overlooked. In this study, we investigate a two-band two-dimensional topological semimetal protected by C4zT magnetic symmetry, exhibiting a two-fold band degeneracy at the Γ(0, 0) and M(π, π) points. Due to the presence of C4zT symmetry, the Brillouin zone is divided into two patches characterized by half-quantized Berry curvature fluxes with opposite signs. In multi-band case, the half-quantization deviates, indicating the fragile nature. The semimetal presents counter-propagating half-edge channels, accompanied by power-law decaying and oscillating edge currents. The band topology leads to unconventional Landau levels featuring anisotropic edge modes. Each massless Dirac cone, associated with the half-quantized Berry curvature flux, exhibits an integer quantum Hall conductance. Additionally, we calculate the local orbital magnetization with open boundary conditions in both the x and y directions. This reveals isolated magnetization islands, highlighting an experimentally observable magnetic phenomenon in this topological semimetal. A two-dimensional semimetal is featured by its low energy physics near the degeneracy points, while the topology over the whole Brillouin zone is rarely studied. The authors find that the Brillouin zone of the C4zT symmetric semimetal is partitioned into two patches characterized by half quantized Berry curvature fluxes with opposite signs, accompanied by the topological transport phenomena. [ABSTRACT FROM AUTHOR]

Kondo physics has long been interesting for studying correlated topology in isolation, as it occurs in heavy fermion compounds where myriad phenomena are well-separated in energy. We introduce magnetic topological Kondo semimetal phases of matter into the literature in this work to advance the understanding of correlated topological semimetal physics by studying a layered three-dimensional heterostructure in which two types of Kondo insulators are stacked alternatingly. In the heterostructures considered, one of these Kondo insulators is SmB6, a potential topological Kondo insulator, and the other one is an isostructural Kondo insulator AB6, where A is a rare-earth element, e.g., Eu, Yb, or Ce. We find that if the latter Kondo insulator orders ferromagnetically, the heterostructure generically becomes a magnetic Weyl Kondo semimetal, while antiferromagnetic order can yield a magnetic Dirac Kondo semimetal. We also confirm the realization of the magnetic Weyl (Dirac) Kondo semimetal phase in density functional theory calculations of the heterostructure of SmB6 and EuB6 (CeB6). Our results demonstrate that Kondo insulator heterostructures are a versatile platform for realizing correlated topological semimetal phases. [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]

Edge states of a topological insulator can be used to explore fundamental science emerging at the interface of low dimensionality and topology. Achieving a robust conductance quantization, however, has proven challenging for helical edge states. In this work, we show wide resistance plateaus in kink states—a manifestation of the quantum valley Hall effect in Bernal bilayer graphene—quantized to the predicted value at zero magnetic field. The plateau resistance has a very weak temperature dependence up to 50 kelvin and is flat within a dc bias window of tens of millivolts. We demonstrate the electrical operation of a topology-controlled switch with an on/off ratio of 200. These results demonstrate the robustness and tunability of the kink states and its promise in constructing electron quantum optics devices. [ABSTRACT FROM AUTHOR]

The article discusses a new protocol for quantum secure direct communication (DI-QSDC) using hyper-entanglement, which ensures secure communication despite device imperfections. The protocol increases the capacity of the secure channel by utilizing hyper-encoding. The article also mentions the AAPPS-DACG Workshop, an international symposium on cosmology and particle astrophysics, and highlights the achievements of Chinese physicist Qi-Kun Xue. Xue has made significant contributions to condensed matter physics, particularly in the study of the quantum anomalous Hall effect (QAHE), and his work has led to advancements in understanding and applying quantum Hall states. Xue has received recognition and prestigious prizes for his achievements in the field of physics. [Extracted from the article]

Ultra‐broadband photodetectors based on semimetal crystals have recently become popular because of their gapless band structures. In particular, semimetal crystals have large carrier mobility or high Seebeck coefficient; this almost eliminates the possibility of using semimetal crystals as photodetectors. In addition, a larger temperature gradient can cause photocurrent generation based on the photothermoelectric effect. Surprisingly, the TaTe2 crystal has a huge absorption coefficient (≈104 cm−1), a minimal specific heat (≈0.172 J g−1 K−1), and a low thermal conductivity (0.3 W m−1 K−1), which is beneficial for generating a high photothermal conversion efficiency of 30.2%, despite its small Seebeck coefficient, and achieving a large temperature gradient occurs for the heat generated by external illumination. Herein, the possibility of photoresponse based on the TaTe2 detector is explored, which has a low carrier mobility (≈10 cm2 V−1 s−1) and a small Seebeck coefficient (≈7.1 µV K−1). The self‐powered TaTe2 photodetector can also provide a competitive photoresponse range from 355 to 2715 nm and exhibit a maximum responsivity of 1.1 mA W−1 with a detectivity of 4.7 × 108 Jones at 455 nm. This study provides a new design scheme and operating mechanism for semimetal photodetectors and enriches semimetal crystal photodetectors. [ABSTRACT FROM AUTHOR]

The non-reciprocal behavior of defect modes of a one-dimensional photonic crystal with two Weyl-semimetal-based defects is investigate by applying the transfer matrix method. The transmission spectrum of the structure exhibits two distinct defect modes. The study shows that these defect modes can be adjusted by altering the thickness of the Weyl semimetal layers and the modulus of the axial vector $ \vec{b} $ b → for both forward- and backward-impinging cases. The peak transmission and frequency of the defect modes are found to be dependent on the thickness of the Weyl semimetal layers, the magnitude of the axial vector $ \vec{b} $ b → , and the impinging direction of the incoming beam. Additionally, the quality factor of the defect modes changes with the thickness of the Weyl semimetal layers and the magnitude of the axial vector $ \vec{b} $ b → but is largely unaffected by reversing the impinging direction of the incoming beam. [ABSTRACT FROM AUTHOR]

Metal contamination in drinking water is well known; however, detailed insights into the metals/metalloids in finished water and their health effects are lacking. Water samples collected over four seasons from August 2022 to April 2023 from three locations in the Yangtze River basin in Nanjing were analyzed using inductively coupled plasma mass spectrometry to detect 33 metal/metalloid types. This study assessed seasonal and spatial variations and evaluated the removal efficiencies of advanced treatment processes. Health risks from metal/metalloid ingestion were calculated using a risk assessment model from the United States Environmental Protection Agency (USEPA). No significant regional differences in total metal/metalloid concentrations were found between the source and finished waters. Metals such as Cr, Ga, Hg, Pb, and Rb varied seasonally, peaking in winter. The advanced treatment process outperformed the conventional process for As removal. However, the removal efficiencies were lower for Mn, Cd, Hg, Se, and Zn than those of the conventional process. Positive correlations were observed among several metals, suggesting that metals may have similar sources of contamination. The main carcinogenic risk exceeded the acceptable levels in children according to the USEPA. Non-carcinogenic risks were below the threshold values, but As, Tl, and V were highlighted as key risk elements. Seasonal changes markedly influenced metal/metalloid concentrations and distributions in water, necessitating risk management focused on arsenic. [ABSTRACT FROM AUTHOR]

As the most prevalent element on our planet, carbon manifests a wide variety of allotropic phases, significantly contributing to its complex physical properties. Recently, several carbon allotropes have been reported to possess abundant topological phases in theory and experiment. This work focuses on a sp3 carbon allotrope, Z-ACA allotrope, which consists of 5-6-7-type Z-ACA carbon rings. This allotrope has been reported previously as a superhard material comparable to diamond. In this study, we report that it is a candidate for both an obstructed atomic insulator and a real Chern insulator. It is worth mentioning that Z-ACA exhibits an unconventional bulk-boundary correspondence due to its hinge boundary state manifestation. Our current research indicates that Z-ACA is a suitable carbon phase platform for studying the real topology and second-order bulk-boundary correspondence. [ABSTRACT FROM AUTHOR]

The manipulation of solid states using intense infrared or terahertz light fields is a pivotal area in contemporary ultrafast photonics research. While conventional circular polarization has been well explored, the potential of counterrotating bicircular light remains widely underexplored, despite growing interest in theory. In the mid-infrared or multi-terahertz region, experimental challenges lie in difficulties in stabilizing the relative phase between two-color lights and the lack of available polarization elements. Here, we successfully generated phase-stable counterrotating bicircular light pulses in the 14–39 THz frequency range circumventing the above problems. Employing spectral broadening, polarization pulse shaping with a spatial light modulator, and intra-pulse difference frequency generation leveraging a distinctive angular-momentum selection rule within the nonlinear crystal, we achieved direct conversion from near-infrared pulses into the designed counterrotating bicircular multi-terahertz pulses. Use of the spatial light modulator enables programmable control over the shape, orientation, rotational symmetry, and helicity of the bicircular light field trajectory. This advancement provides a novel pathway for the programmable manipulation of light fields, and marks a significant step toward understanding and harnessing the impact of tailored light fields on matter, particularly in the context of topological semimetals. Phase-stable counterrotating bicircular light pulses, including a trefoil-like field trajectory, were realized in multi-terahertz range. Orientation, shape, rotational symmetry, and helicity of trajectories are programmable on software. [ABSTRACT FROM AUTHOR]

A two-dimensional (2D) Weyl semimetal, akin to a spinful variant of graphene, represents a topological matter characterized by Weyl fermion-like quasiparticles in low dimensions. The spinful linear band structure in two dimensions gives rise to distinctive topological properties, accompanied by the emergence of Fermi string edge states. We report the experimental realization of a 2D Weyl semimetal, bismuthene monolayer grown on SnS(Se) substrates. Using spin and angle-resolved photoemission and scanning tunneling spectroscopies, we directly observe spin-polarized Weyl cones, Weyl nodes, and Fermi strings, providing consistent evidence of their inherent topological characteristics. Our work opens the door for the experimental study of Weyl fermions in low-dimensional materials. 2D Weyl semimetals are spin-polarized analogues of graphene that promise access to various topological properties of matter. Here, the authors evidence spin-polarized Weyl cones, Weyl nodes, and Fermi strings in monolayer bismuthene. [ABSTRACT FROM AUTHOR]

The valley-polarized quantum anomalous Hall (VP-QAH) materials, which combine valley polarization and the quantum anomalous Hall (QAH) effect, are of both fundamental and technological importance due to their potential applications for nanoscale devices. Here, we explored the stability, magnetic, and topological properties of two-dimensional MnTiX2 (X = F/Cl/Br) monolayers based on first-principles calculations. Our results show that all the structures have robust antiferromagnetic orders with large magnetic anisotropic energies and high transition temperatures (480–670 K). In the absence of spin–orbital coupling (SOC), the MnTiX2 monolayers represent antiferromagnetic quadratic crossing semimetals. In the presence of SOC, the quadratic crossing points of the systems are opened with sizable bandgaps (> 0.5 eV), and they are transformed to be QAH insulators with |C| = 1. Moreover, the MnTiF2 monolayer is found to be a spontaneous VP-QAH semiconductor due to the time reversal symmetry and inversion symmetry being broken. These insights provide an ideal platform for achieving VP-QAH materials for dissipationless transport and quantum computing. [ABSTRACT FROM AUTHOR]

[Display omitted] Owing to the outstanding properties provided by nontrivial band topology, topological phases of matter are considered as a promising platform towards low-dissipation electronics, efficient spin-charge conversion, and topological quantum computation. Achieving ferroelectricity in topological materials enables the non-volatile control of the quantum states, which could greatly facilitate topological electronic research. However, ferroelectricity is generally incompatible with systems featuring metallicity due to the screening effect of free carriers. In this study, we report the observation of memristive switching based on the ferroelectric surface state of a topological semimetal (TaSe 4) 2 I. We find that the surface state of (TaSe 4) 2 I presents out-of-plane ferroelectric polarization due to surface reconstruction. With the combination of ferroelectric surface and charge-density-wave-gapped bulk states, an electric-switchable barrier height can be achieved in (TaSe 4) 2 I-metal contact. By employing a multi-terminal-grounding design, we manage to construct a prototype ferroelectric memristor based on (TaSe 4) 2 I with on/off ratio up to 103, endurance over 103 cycles, and good retention characteristics. The origin of the ferroelectric surface state is further investigated by first-principles calculations, which reveal an interplay between ferroelectricity and band topology. The emergence of ferroelectricity in (TaSe 4) 2 I not only demonstrates it as a rare but essential case of ferroelectric topological materials, but also opens new routes towards the implementation of topological materials in functional electronic devices. [ABSTRACT FROM AUTHOR]

Topological invariants are crucial quantities for classifying materials with topological phases. Hence, their connections with experimentally measurable quantities are extremely important. In this context, circular dichroism (CD) provides a protocol to detect the Chern number 0 of the lowest energy Bloch band (LBB) of a semimetal. This hinges on the unequal depletion rates of the Bloch electrons from a filled LBB, under the action of a time-periodic circular drive, depending on the chirality of the polarization. According to the dimensionality of the system (i.e., whether it is two- or three-dimensional), the integrated differential rate for depletion has to be formulated a bit differently in order to relate it to 0 . Our aim is to capture the nature of the CD response for semimetals with anisotropic band dispersions. We show that while the quantization of the CD response for the three-dimensional cases is strongly sensitive to anisotropy, the two-dimensional counterparts show a perfectly quantized response. [ABSTRACT FROM AUTHOR]

Nanoporous graphene (NPG) materials are generated by removing internal degree-3 vertices from graphene and introducing nanopores with specific topological structures, which have been widely explored and exploited for applications in electronic devices, membranes, and energy storage. The inherent properties of NPGs, such as the band structures, field effect mobilities and topological properties, are crucially determined by the geometric structure of nanopores. On-surface synthesis is an emerging strategy to fabricate low-dimensional carbon nanostructures with atomic precision. In this review, we introduce the progress of on-surface synthesis of atomically precise NPGs, and classify NPGs from the aspects of element types, topological structures, pore shapes, and synthesis strategies. We aim to provide a comprehensive overview of the recent advancements, promoting interdisciplinary collaboration to further advance the synthesis and applications of NPGs. On-surface synthesis is a useful approach for the construction of nanoporous graphene materials, which are in turn of interest for various electronic applications. Here, the authors review the latest developments in the on-surface synthesis of atomically precise pristine and hetero-atom doped nanoporous graphene materials. [ABSTRACT FROM AUTHOR]

The bulk photovoltaic effect (BPVE) in non-centrosymmetric materials has attracted significant attention in recent years due to its potential to surpass the Shockley-Queisser limit. Although these materials are strictly constrained by symmetry, progress has been made in artificially reducing symmetry to stimulate BPVE in wider systems. However, the complexity of these techniques has hindered their practical implementation. In this study, we demonstrate a large intrinsic photocurrent response in centrosymmetric topological insulator Ag2Te, attributed to the surface photogalvanic effect (SPGE), which is induced by symmetry reduction of the surface. Through diverse spatially-resolved measurements on specially designed devices, we directly observe that SPGE in Ag2Te arises from the difference between two opposite photocurrent flows generated from the top and bottom surfaces. Acting as an efficient SPGE material, Ag2Te demonstrates robust performance across a wide spectral range from visible to mid-infrared, making it promising for applications in solar cells and mid-infrared detectors. More importantly, SPGE generated on low-symmetric surfaces can potentially be found in various systems, thereby inspiring a broader range of choices for photovoltaic materials. The bulk photovoltaic effect holds promise for various optoelectronic applications, but it is usually restricted to non-centrosymmetric materials operating in the visible range. Here, the authors report a surface photogalvanic effect spanning from visible to midinfrared wavelengths in a centrosymmetric topological insulator, Ag2Te. [ABSTRACT FROM AUTHOR]

Contamination by metals poses a significant threat to marine ecosystems and the health of marine organisms, including cetaceans. This study aimed to assess the concentrations of some metal and metalloids in the skin of bottlenose dolphins (Tursiops truncatus) from the Yucatan Peninsula in Mexico using Flame Atomic Absorption (FAA) spectrometry. A total of 41 skin samples were collected, comprising 22 samples from Yucatán in the Gulf of Mexico and 19 samples from Chetumal Bay in the Caribbean. The results of our analysis revealed the presence of various elements in the skin of bottlenose dolphins from coastal waters in the Yucatan Peninsula. Among the detected metals, zinc (Zn), iron (Fe), and arsenic (As) exhibited notable concentrations, with the order of abundance being Zn > Fe > As > Cu > Cr > Cd > Ni. The elevated concentrations of Zn and Fe suggest potential exposure and accumulation of these metals in the studied dolphin population. Interestingly, measurable concentrations of lead (Pb) and manganese (Mn) were not detected in the skin samples, indicating either low levels or the absence of their accumulation in the studied dolphin populations. The absence of measurable Pb concentrations is particularly encouraging as Pb is known to have detrimental effects on marine organisms and is commonly associated with anthropogenic activities. This study provides valuable insights into the metal contamination status in bottlenose dolphins from the Yucatan Peninsula, Mexico. The notable concentrations of Zn, Fe, and As raise concerns about potential health risks to these charismatic marine mammals. Further research is warranted to investigate the sources and pathways of heavy metal exposure in this population and to understand the potential consequences of such exposure on the health and well-being of bottlenose dolphins in the Yucatan Peninsula. [ABSTRACT FROM AUTHOR]

In graphene on transition metal dichalcogenides, two types of spin–orbit coupling (SOC)—Rashba and spin–valley Zeeman SOCs—can coexist that modify graphene's electronic band differently. Herein, it is shown that the Landau levels (LLs) are also affected by these SOCs distinctively enough to estimate their relative strengths from the Landau fan diagram. A simple theoretical model is used to calculate the LL spectra of graphene for different SOC strengths, revealing that when the total SOC is strong enough (i.e., when it is comparable to the half of the energy gap between the LLs of an intrinsic graphene), the corresponding LLs will split and cross with others depending sensitively on the relative strengths of the SOC terms. To demonstrate how one can use it to estimate the relative SOC strengths, the four key features that are well separated from the complex background are first identified and compared with experiment to show that in the sample investigated, the Rashba SOC is stronger than the spin–valley Zeeman SOC consistent with other spectroscopic measurements. The study therefore provides a simple and practical strategy to analyze the LL spectrum in graphene with SOC before carrying out more in‐depth measurements. [ABSTRACT FROM AUTHOR]

Heavy metal and metalloid pollution in reservoir systems has attracted widespread attention due to their toxic, persistent, and nonbiodegradable characteristics. This study investigated the distribution and risks of heavy metals and metalloids in the sediment and drawdown area of the Fengshuba reservoir system. Sediment phase exhibited substantial heavy metal and metalloid pollution and higher ecological risk that the drawdown phase. There were significant differences in the structure and composition of the total metal content and the bioavailable fraction between the sediment and the drawdown area, which indicates that the total metal content and the bioavailable fraction might dominantly regulate by a complex combination of sediment characteristics. Positive Matrix Factorization model was used to identify sources of heavy metals and metalloids pollution and revealed that heavy metals and metalloids contamination in Fengshuba reservoir might originate from anthropogenic activities. Evaluations from risk assessment show that As and Cd in the reservoir system may pose health risks. Knowledge of distribution, potential risk assessment, and source apportionment of heavy metals and metalloids in the Fengshuba drinking water is critical in promoting the sustainable development of the reservoir, developing water management and conservation strategies in the Fengshuba reservoir. [ABSTRACT FROM AUTHOR]

Decades ago, Gurzhi proposed that if momentum-conserving collisions prevail among heat-carrying phonons in insulators and charge-carrying electrons in metals, hydrodynamic features will become detectable. In this paper, we will review the experimental evidence emerging in the last few years supporting this viewpoint and raising new questions. The focus of the paper will be bulk crystals without (or with a very dilute concentration of) mobile electrons and steady-state thermal transport. We also discuss the possible link between this field of investigation and other phenomena, such as the hybridization of phonon modes and the phonon thermal Hall effect. [ABSTRACT FROM AUTHOR]

The presented study suggests a silicon photonic topological insulator with triple Dirac points, each associated with a specific valley; there is a contrast in the chirality (handedness) of the photon states between these valleys. This contrasting chirality results in interesting optical properties, potentially leading to topologically protected robust wave guiding effect in compact structure with sharp edge. [ABSTRACT FROM AUTHOR]

We report interfacial transport properties in in situ grown orthorhombic perovskite oxide heterostructures consisting of an antiferromagnetic insulator DyFeO3 and a paramagnetic conductor CaRuO3. We observe Hall effect with a step-like increase amounting to an effective magnetic field of 30 T at 20 K. We provide a plausible explanation in the context of topological Hall effect originating from a non-coplanar spin texture and resultant emergent field in DyFeO3 associated with the scalar spin chirality. Our results demonstrate that the proximity effect of the emergent field at heterointerfaces is a universal physical phenomenon, while it has been reported originally in a heterointerface composed of pyrochlore oxides. This will greatly expand the choice of materials to the heterointerfaces for the research in emergent transport phenomena, which has been limited to single compounds with both metallic properties and special spin textures. Additionally, this will pave the way for possible device application of the emergent field by designing and combining perovskite oxides with versatile functionalities such as multiferroicity. [ABSTRACT FROM AUTHOR]

In the present study, first-principles molecular dynamics simulations were employed to study the effects of small amounts of B and C substituted for P on the structure and magnetic properties of Fe80P13C7, Fe80P10C7B3, and Fe80P8C9B3 amorphous alloys. A small amount of B and C replacing P atoms increases the icosahedral structure of the amorphous alloys, especially the increase in the regular icosahedral structure. The saturation magnetization of the three kinds of amorphous alloys gradually increases with the addition of B and C atoms, and the results of experimental and simulated calculations show consistent trends. The substitution of P atoms by B and C atoms leads to the aggregation of Fe atoms, which increases the magnetic moment of the iron atoms. In addition, the improvement of local structural symmetry may be one of the reasons for the increase in saturation magnetization of amorphous alloys. The substitution of a small number of B and C atoms plays an important role in improving the saturation magnetization of the amorphous alloy, which has a certain guiding significance for the development of amorphous alloys with excellent soft magnetic properties. [ABSTRACT FROM AUTHOR]

The USEPA issued the "Framework for Metal Risk Assessment" in 2007, recognizing that human and environmental exposure to metals and metalloids (MMEs) poses challenges risk assessment. Inhalation of aerosols containing MMEs is a primary pathway for exposure in the occupational setting, for consumer exposure, and to general population exposure associated with point‐source emissions or ambient sources. The impacts of inhalation can be at the point of deposition (local exposure) or may manifest after uptake into the body (systemic exposure). Both local and systemic exposure can vary with factors that determine the regional deposition of MME‐containing aerosols. Aerosol characteristics such as particle size combine with species‐specific characteristics of airway morphology and lung function to modulate the deposition and clearance of MME particulates. In contrast to oral exposure, often monitored by measuring MME levels in blood or urine, inhalation exposure can produce local pulmonary impacts in the absence of significant systemic distribution. Exposure assessment for nutritionally essential MMEs can be further complicated by homeostatic controls that regulate systemic MME levels. Predictions of local exposure can be facilitated by computer models that estimate regional patterns of aerosol deposition, permitting calculation of exposure intensity in different regions of the respiratory tract. The utility of deposition modeling has been demonstrated in assessments of nutritionally essential MMEs regulated by homeostatic controls and in the comparison of results from inhalation studies in experimental animals. This facilitates extrapolation from animal data to humans and comparisons of exposures possessing mechanistic linkages to pulmonary toxicity and carcinogenesis. Pulmonary deposition models have significantly advanced and have been applied by USEPA in evaluations of particulate matter. However, regional deposition modeling has yet to be incorporated into the general guidance offered by the agency for evaluating inhalation exposure. Integr Environ Assess Manag 2024;20:952–964. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Key Points: The USEPA is urged to promote the application of models for regional deposition in assessing impacts of inhalation exposure to metal and metalloid particulate matter.The local and systemic impacts of inhaled metals and metalloids are determined by patterns of regional deposition in the respiratory tract. [ABSTRACT FROM AUTHOR]

The emerging field of photonic topological insulators offers promising platforms for high-performance optical communication, computing, and sensing. However, conventional photonic topological insulator designs typically operate within the diffraction limit due to their dielectric nature. This limitation imposes constraints on device miniaturization, reduces light–matter interaction, and decreases overall device sensitivity. Introducing a new valley-Hall hybrid plasmonic topological insulator, we overcome this limitation by exploiting the coupling of surface plasmon oscillations with the optical modes of a dielectric photonic crystal, allowing for sub-diffraction vertical confinement of light. Deep-subwavelength chiral edge states can, therefore, be generated and robustly guided along disordered Z-shaped topological boundaries with much lower propagation loss compared to purely plasmonic platforms. Such extreme manipulation of light on an integrated chip platform maximizes light–matter interaction and opens the door for truly compact and efficient optical modulators, molecular sensors, and next-generation nanophotonic and quantum devices. [ABSTRACT FROM AUTHOR]

Both biochars (BCs) and modified-biochars (MBCs) for toxic-metal/metalloid ions (TMIs) removal from water have caught much attention owing to their exceptional properties such as eco-friendly, low-carbon emission and cost-effective. However, reviews on the exploration of theoretical models of BCs and MBCs in various systems are unobtainable. To give a summary of theoretical models on BCs and MBCs for TMIs removal in various solution systems, this review will center on some typical kinetic and isotherm equations of BCs and MBCs for TMIs sorption in a single, mixed, mixed metal ions/organic substance solutions. Typically, two-parameter and threeparameter kinetic and isotherm equations of BCs and MBCs for TMIs sorption were stressed. The comparisons of these models in various solution systems were drawn. It was found that P-2nd-O kinetic model, Langmuir and Freundlich isotherm models are the dominating adsorption manners for TMIs in various MSSs. Especially, only the kinetic models of Cu(II), Pb(II), Cr(VI) and Cd(II) sorption, as well as the isotherms of Cu(II) and Cd(II) sorption on BCs and MBCs were reported in these MSSs. We hope such a summary will be favorable for the accurately selecting of optimal models to explain the sorption processes in different metal-solution systems. [ABSTRACT FROM AUTHOR]

The 8 × 8 magneto-optical matrix has been derived to discuss the Faraday rotation (FR) effect, which is induced by the linear polarization wave passing through a sandwich structure composed of a dielectric layer and two identical Weyl semimetals (WSMs). The giant enhanced FR angle about 45° can be realized at the resonant tunneling wavelength of right hand circularly polarization (RCP) waves by enlarging the difference of the resonant tunneling wavelength of RCP and left hand circularly polarization waves suitably. It is shown that the resonant wavelengths depend on the Weyl node separation and tilt degree of Weyl cones in both type-I and type-II WSMs. More importantly, there exists a tunable one-to-one relationship between the Weyl node separation and the wavelength of the resonant FR angle, as well as the tilt degree and the wavelength of the resonant FR angle, which enables the characteristic of the Weyl node separation and tilt degree. Our research reveals an available method to determine the Weyl node separation and tilt degree of Weyl cones in both type-I and type-II WSMs. [ABSTRACT FROM AUTHOR]

In recent years, the skyrmion lattice phase with a short lattice constant has attracted attention due to its high skyrmion density, making it a promising option for achieving high-density storage memory and for observing novel phenomena like the quantized topological Hall effect. Unlike conventional non-centrosymmetric systems where the Dzyaloshinsky–Moriya interaction plays a crucial role, the short pitch skyrmion phase requires a quadratic magnetic interaction J (q) with a peak at finite- Q , and weak easy-axis magnetic anisotropy is also critical. Thus, conducting first-principles evaluations is essential for understanding the formation mechanism as well as for promoting the discovery of new skyrmion materials. In this Perspective, we focus on recent developments of the first-principles evaluations of these properties and apply them to the prototype systems Gd T 2 X 2 and Eu T 2 X 2 , where T denotes a transition metal and X represents Si or Ge. In particular, based on the spin density functional theory with the Hubbard correction combined with the Liechtenstein method in the Wannier tight-binding model formalism, we first show that the Hubbard U and Hund's coupling is essential to stabilize a skyrmion lattice state by enhancing the easy-axis anisotropy. We then discuss mechanisms of finite- Q instability and show that competition among Gd-5 d orbitals determines whether ferromagnetism or a finite- Q structure is favored in Gd T 2 Si 2 with T = Fe and Ru. Our systematic calculations reveal that GdRu 2 X 2 , GdOs 2 X 2 , and GdRe 2 X 2 are promising, while GdAg 2 X 2 , GdAu 2 X 2 , and EuAg 2 X 2 are possible candidates as the skyrmion host materials. Analysis based on a spin spiral calculation for the candidate materials is also presented. [ABSTRACT FROM AUTHOR]

Structural, electronic, magnetic and optical properties of Cu4Mn2Te4 have been reported earlier by the authors, and here, the transport properties of the same are discussed along with the band structure investigation of the neodymium-doped cubic material LMO (LiMn2O4), namely LiMn 1. 7 5 Nd 0. 2 5 O4 compound, under spin polarized schemes through the First Principles calculations. The Full Potential-Linearized Augumented Plane Wave Method (FP-LAPW) method is adopted to investigate the electronic structures based on the framework of Density Functional Theory (DFT). Exchange potentials are treated using the Generalized Gradient Approximations (GGA). Cohesive energy calculations reveal that the ferromagnetic phase of LiMn 1. 7 5 Nd 0. 2 5 O4 and the antiferromagnetic phase of Cu4Mn2Te4 exhibits a stable phase. Of these, FM-LiMn 1. 7 5 Nd 0. 2 5 O4 shows a semi-metallic-like behavior in spin-up channel and metallic behavior in spin-down channel whereas antiferromagnetic Cu4Mn2Te4 exhibits a band gap in both spin-up and spin-down channels. Dirac points are identified at −0.0625 eV in the band structure plot of FM-LiMn 1. 7 5 Nd 0. 2 5 O4 at its high symmetry points Γ and W which is an indication of high electron mobility at ambient condition. The presence of flat and dispersive bands around the Fermi energy level is an indication of high thermopower, and it is present in both the compounds FM-LiMn 1. 7 5 Nd 0. 2 5 O4 and AFM-Cu4Mn2Te4. From the present computations, at 300 K, a power factor range of ( S 2 σ scaled by relaxation time in μ W/msK2) 1. 7 5 × 1 0 2 0 ↑ and 9. 3 7 × 1 0 2 1 ↓ is obtained for ferromagnetic LiMn 1. 7 5 Nd 0. 2 5 O4 compounds at up and down spins, respectively. A typical power factor (μ Wm − 1 s − 1 K − 2 ) of 4. 7 9 × 1 0 1 5 ↑ and 2. 9 7 × 1 0 1 8 ↓ is obtained for antiferromagnetic Cu4Mn2Te4 at 325 K required for good thermoelectric performance. [ABSTRACT FROM AUTHOR]

We have investigated magnetic interactions between transition metal ions in bismuthene topological insulators with protected edge states. We find that these topological states have a crucial role in the magnetic interactions in 2D topological insulators. Using first-principles and model Hamiltonian, we make a comparative study of transition metal doped bulk and nanoribbon bismuthene. While a direct overlap between the transition metal prevails in gapped bulk bismuthene, at the borders of nanoribbons, a long-range magnetism is present. The exchange interactions are well described by a Ruderman–Kittel–Kasuya–Yosida-like Hamiltonian mediated by massive and topological states. Our results show a dominance of antiferromagnetism promoted by the topological states, preserving the spin-locked Dirac crossing states due to a global time-reversal symmetry preservation. This extended magnetic interactions mediated mainly by massless electrons can increase the spin diffusion length being promising for fast dissipationless spintronic devices. [ABSTRACT FROM AUTHOR]