Search

The strong interaction between graphene and elemental ferromagnetic transition metals results in considerable shifts of the graphene π band away from the Fermi level. At the same time, a weakly-dispersing single-spin conical band feature is found in the proximity of the Fermi level at the K ̄ point in the surface Brillouin zone of epitaxially-aligned graphene/Co(0001). Here, the robustness of this electronic state against twisting angles at the interface is experimentally and theoretically demonstrated by showing the presence of similar band features also in the case of rotated graphene domains on Co(0001). Spin-resolved reciprocal space maps show that the band feature in rotated graphene has similar Fermi velocity and spin polarization as its counterpart in epitaxially-aligned graphene. Density functional theory simulations carried out for the experimentally observed graphene orientations, reproduce the highly spin-polarized conical band feature at the graphene K ̄ point, characterized by a hybrid π -d orbital character. The presence of the conical features in the rotated domains is attributed to the unfolding of the superstructure K ̄ point states exclusively to the K ̄ point of the graphene primitive cell. The similarities found in the electronic character for different graphene orientations are crucial in understanding the magnetic properties of realistic graphene/Co interfaces, facilitating their implementation in spintronics applications. [Display omitted] [ABSTRACT FROM AUTHOR]

This study employs density functional theory (DFT) using Wien2k to comprehensively analyze the essential properties of two half-Heusler alloys, KCrSi and KCrGe. Our findings demonstrate that the ferromagnetic Type 2 configuration exhibits superior stability over non-magnetic and antiferromagnetic states for all KCrZ (Z = Si, Ge) alloys. These alloys exhibit complete spin polarization and half-metallic character, with calculated magnetic moments of 3 μB for both KCrSi and KCrGe. The Curie temperature (T C) is determined using the mean field approximation. Mechanical stability is assessed through second-order elastic constants (SOECs), and electronic properties are analyzed using local spin density approximation (LSDA), Perdew-Burke Generalized Gradient Approximation (PBE-GGA), and Tran-Blaha modified Becke-Johnson (TB-mBJ) schemes, confirming the retention of the half-metallic nature. The negative enthalpy of formation (ΔH) suggests material stability. The use of semi-classical Boltzmann theory, incorporated through the sophisticated scheme of BoltzTraP, explores transport coefficients. High pressures and temperature discrepancies in thermodynamics are considered by implementing the quasi-harmonic Debye approximation to illustrate stability. Finally, optical properties are summarized to assess the applicability of this alloy for optoelectronic applications. The overall characteristics of these particular alloys suggest potential applications in sustainable thermoelectric and optoelectronic features. • The stability in cubic structure is established with the help of structural optimization, and mechanical stability criteria. • The high Seeback coefficient and low thermal conductivity yield a high figure of merit ZT at 900 K. • The alloy has potential applications in thermoelectric technology and optoelectronic devices. [ABSTRACT FROM AUTHOR]

The structure and the thermophysical properties of δ -UZr 2 are investigated using 0 K density functional theory and ab initio molecular dynamics (AIMD). Modeling the true paramagnetic state of this intermetallic compound has been challenging using first-principles calculations. For the first time, we find that the generalized gradient approximation method without applying an on-site Coulomb interaction term (Hubbard U) can result in a ground state that is antiferromagnetic (AFM). We believe that this weak AFM ground state is the closest to the real paramagnetic state. We found that structure optimization at finite temperatures using AIMD is necessary to achieve this ground state instead of the non-magnetic and ferromagnetic states previously reported in the literature. Our findings indicate that applying the Hubbard U on uranium f -orbitals in this metallic system is unnecessary and not recommended, as it leads to a large overestimation of the volume and introduces an unphysical strong spin polarization. Our approach results in atomic volume, thermal expansion, and heat capacities that have strong agreement with experiments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Be 2 CrH 6 , and Be 2 CrH 6 have hydrogen storage capacities 7.9 wt%, and 7.6 wt%, • Spintronic and energy harvesting applications. • The ferromagnetism by electron spin instead of magnetic ion clustering. • The Half-metallic ferromagnetism ensures 100% spin polarization. • Large power factor and least lattice thermal conductivity. Metal hydrides are highly significant for hydrogen storage because of high gravimetric and kinetic factors. Therefore, the double perovskites hydrides Be 2 XH 6 (X = Cr and Mn) have outstanding hydrogen storage capability with gravimetric hydrogen densities of 7.9 wt% and 7.6 wt%, respectively. Moreover, the DFT-based PBE-GGA and TB-mBJ potential have been implemented to systematically analyze the electronic, Curie temperature, and magnetic characteristics of Be 2 XH 6 (X = Cr and Mn). The tolerance factor and formation energy analysis indicate the structural and thermodynamic stabilities. The band structures, density of states and Curie Weiss law ensure the above room temperature half metallic ferromagnetism with complete spin polarization. The ultralow lattice thermal conductivity and high thermoelectric performance also significantly increase their importance. Finally, the mechanical and thermodynamic behavior have also been addressed in detail. These conclusions are significant for future hydrogen storage growth increases in metal hydrates. [ABSTRACT FROM AUTHOR]

• The spin-dependent electronic transport properties of zigzag phosphorene nanoribbons (ZPNRs);. • The electronic transport through the ZPNRs shows apparent spin polarization;. • The spin polarization is tightly dependent on the absorbing manners;. • Negative differential resistance characteristic can be observed on current-voltage curves. Based on density functional theory (DFT) and non-equilibrium Green's function (NEGF) method, we have investigated spin-dependent electronic transport properties of zigzag phosphorene nanoribbons (ZPNRs) coupled with chromium triiodide (CrI 3) molecules. Three different adsorption models have been considered: CrI 3 molecule is placed on ZPNR surface (C-type), and CrI 3 molecule is lateral adsorbed on the edge of ZPNR with its molecule panel vertical (V-type) or parallel (P-type). We discovered that ZPNR's electrical transport clearly displays spin polarization, owing to the coupling between ZPNR and CrI 3 molecules. And spin-polarization is tightly dependent on the absorbing manners. Moreover, the negative differential resistance (NDR) characteristics can be observed from current-voltage curves and modulated by absorbing molecules. Furthermore, we also discovered that CrI 3 is vertically adsorbed on the surface of the ZPNRs has a better spin-polarization efficiency than the other two cases. [ABSTRACT FROM AUTHOR]

The ability of organic radicals to maintain their open-shell feature in the device environment directly determines whether they can act as spin filters. Based on the recently synthesized stable VR-1 radical, we have designed two molecular devices with symmetric and asymmetric molecule-electrode connections and investiaged their spin-polarized transport properties using density functional theory and non-equilibrium Green's function methodology. The results show that the presence of unpaired electron in VR-1 radical is not a sole requirement for causing spin polarization and the molecular-electrode connection mode plays a decisive role in the transport characteristics. VR-1 can be used as a spin filter in the asymmetric connection mode, while it loses its open-shell feature in the symmetric connection mode. Moreover, VR-1 with the asymmetric connection mode exhibits obvious spin-rectifying effect. The results are analyzed by the spin-resolved frontier molecular orbitals and eigenstates, Mulliken population analysis, transmission spectra and transmission eigenstates. [ABSTRACT FROM AUTHOR]

A possibility of appearance of antiferromagnetic ordering in armchair carbon nanotubes and graphene is studied using density functional theory within a DFT+U approach. It is shown that the Coulomb repulsion between electrons in the π -orbitals of graphene would need to reach a threshold value of U c = 3. 6 eV , in order to stabilize the antiferromagnetic order and an energy gap in an electron spectrum at the Fermi level. In the carbon nanotubes the threshold value U c for appearance of the antiferromagnetism decreases with the nanotube's diameter. For an intermediate value of U < U c the dependence of the energy gap on the diameter of nanotube is well described by a power law in agreement with earlier experimental findings. The antiferromagnetism in the carbon nanotubes is suppressed by departure of the Fermi level from a neutrality point. The latter result can qualitatively explain experimentally observed gate voltage dependence of the energy gap in junctions with the suspended carbon nanotubes as well as the absence of the energy gap in junctions with nanotubes deposited on some substrates. • Carbon nanotubes (CNTs) under influence of gate voltage are studied with a DFT+U method. • Hubbard U stabilizes an antiferromagnetic order with a quasiparticle energy gap in the CNTs. • The computations explain observed gate voltage dependence of the gap in ultraclean CNTs. [ABSTRACT FROM AUTHOR]

[Display omitted] The quaternary Heusler alloys with composition LiAEFeSb have been studied in this manuscript (AE = Alkaline Earth elements Be, Mg, Ca, Sr and Ba) for their potential applications in spintronics. All the investigations have been performed by employing density functional theory. A systematic comparison of results obtained within local density approximation (LDA) and the generalized gradient approximation (GGA) done. Our calculations reveal that all the studied alloys have lowest energy in type-I arrangement of basis and exhibit interesting electronic and magnetic properties. All the alloys exhibit a stable ferromagnetic ground state. Fixed spin moment calculations rule out existence of any other local magnetic minima. The phonon dispersions show that all the alloys except LiBeFeSb are dynamically stable. Notably, LiSrFeSb and LiBaFeSb exhibit half-metallic electronic band structure and 100 % spin polarization making them suitable choice for promising spintronic applications such as spin filter and detectors. [ABSTRACT FROM AUTHOR]

The spintronic is an emerging technology which controls the properties of multifactional devices with spin of electrons. In present manuscript, Wien2k and Boltz Trap codes are used to explore electronic, magnetic, and thermoelectric characteristics of Sr 2 CrXO 6 (X = Nb, Mo) double perovskites (DPs). The evaluation of energies released in paramagnetic (PM), antiferromagnetic (AFM), and ferromagnetic (FM) states assure the stability of FM states. Both the negative formation energy and the tolerance factor confirm structural and thermodynamic stability in FM states. The 100 % spin polarization was confirmed by both integer values of magnetic moment (MM) and the spin polarization factor. The values of exchange energy, double exchange model, hybridization of p-d states, and exchange constants are calculated to explore the nature of ferromagnetism and spin functionality. The effect of thermoelectric parameters on spin of electrons and thermoelectric performance are elaborated by thermal to electrical conductivity ratio, Seebeck coefficient and power factor. • High Curie temperature, and spintronic applications. • Spin of electrons overcome the charge with multifuctional properties. • Double exchange mechanism confirms the ferromagnetism by electron spin instead of magnetic ion clustering. • Half metallic ferromagnetism and 100 % spin polarization. • Large value of electrical conductivity and low values of thermal conductivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • The electronic and magnetic properties of pristine and defected sheets before and after Sc metal decoration are investigated. • The E g values are reduced in the order of pristine(2.01 eV) > 55-77 (1.90 eV) > 5–8-5(1.90 eV) > 4-55-7777(0.58 eV). • The Sc-1 metal decoration produces one unpaired electron to the complex which transforms it to the magnetic state. • The highest spin polarization of P = 4.15 in Pristine_A and P = 3.41 in the 4-55-7777_I complex is obtained. To scrutinize the electronic and magnetic properties of fluorinated pristine, stone wales, di-vacancy, and two stone wales defected graphene sheets by scandium (Sc) metal decoration, the density functional theory is used. The obtained maximum binding and interaction energy values confirm that the two Sc metals decorated on the direct top and bottom of pentagonal rings of the two stone wales graphene sheet have stronger interactions than others. To validate the interactions, natural population analysis and electron density difference map are performed, revealing that Sc metal is the electron donor in all complexes. After the formation of defects in the pristine sheet, energy gap values are reduced in the defected sheets. The density of states infers the shift in the fermi level of all complexes after defect formation and metal decoration. The ultraviolet–visible spectral analysis exposes the highest absorption peaks of all bare sheets at the UV region and after Sc metal decoration, the peaks get red shifted. The results show that Sc metal decorated on two stone wales graphene sheet interacts better with Sc metals than other complexes. The decoration of single Sc metal in all four bare sheets transforms the sheet from a non-magnetic to a magnetic state but when two Sc metals are decorated it became non-magnetic. The highest degree of spin polarization, P = 4.15 is obtained while decorating a single Sc metal on the hexagonal ring of the pristine sheet. The outcome of this work suggests that Sc metal decoration on pristine and defected graphene sheets has great potential to improve the electronic and magnetic properties of graphene for designing spintronic and data storage devices. [ABSTRACT FROM AUTHOR]

Using first principles total energy calculation with the approach of density functional theory (DFT) and DFT + U calculations, the structural and electronic properties of erbium copper (ErCu) intermetallic compound were studied. In the present work, we used the local density approximation for the exchange and correlation potential for the spin polarized case. The structural optimization shows that ErCu is stable in the cubic structure. The obtained ground state properties viz; lattice constant a o (a.u), bulk modulus B (GPa) and magnetic moment (μ B), which show good comparison with the available experimental data. We have also investigated the electronic properties such as electronic band structure, density of states, Fermi surfaces and charge density of states for spin-polarized case. In the band structure, majority spins energies contributions are higher than the minority spins energies contribution. The total density of states (TDOS) show that near the Fermi level, is mostly dominated by Er 'f' orbital electrons and below the Fermi level, are due to Cu '3d' orbital electrons. The charge distributions of ErCu are ranging between +0.0003 e/Å3 to +0.0693 e/Å3 for majority channels and +0.0003 e/Å3 to +0.0715 e/Å3 for the minority spin channels. • Spin polarized data of structure and electronic properties of B2-type ErCu are reported using DFT and DFT+U. • With spin polarization, good agreement of obtained ground state properties with available data. • Majority spins energies contributions are higher than the minority spins energies contribution. • The ' f ' states of Er and ' d ' states of Cu play an important role in band structures and Fermi surfaces of ErCu. [ABSTRACT FROM AUTHOR]

• Fully Relativistic PAW band structure of Re(0001) surface. • Identification of surface states and resonances. • Analysis and discussion of the spin-polarization of the surface states. • Comparison with the surface states of Au(111), Pt(111), Ir(111), and Os(0001). We study the electronic structure of the Re(0001) surface by means of ab-initio techniques based on the Fully Relativistic (FR) Density Functional Theory (DFT) and the Projector Augmented-Wave (PAW) method. We identify the main surface states and resonances and study in detail their energy dispersion along the main symmetry lines of the SBZ. Moreover, we discuss the effect of spin-orbit coupling on the energy splittings and the spin-polarization of the main surface states and resonances. Whenever possible, we compare the results with previously studied heavy metals surfaces. We find empty resonances, located below a gap similar to the L-gap of the (111) fcc surfaces, that have a downward dispersion and cross the Fermi level, similarly to the recently studied Os(0001) surface. Their spin polarization at the Fermi level is similar to that predicted by the Rashba model, but the usual level crossing at Γ ¯ is not found with our slab thickness. Moreover, for selected states, we follow the spin polarization along the high symmetry lines, discussing its behavior with respect to k ∥ , the wave-vector parallel to the surface. [ABSTRACT FROM AUTHOR]

In this paper, we study the structural, electronic, magnetic, mechanical and thermal properties of Half-Heusler CoMnTe, using the Density Functional Theory (DFT) with the generalized gradient approximation (GGA) and GGA plus the Hubbard correction (GGA+U). The obtained results show that the compound is more stable in γ -phase with the ferromagnetic (FM) configuration than the nonmagnetic (NM) among the three considered structural phases (α , β , γ) and there is no possibility of martensitic transformation under the tetragonal distortion effect. The computed total magnetic moments of CoMnTe by GGA and GGA+U are 4 μ B and 4.13 μ B , respectively, arising mainly from the Mn atom. The obtained density of states and band structures using GGA approach show that the compound exhibits half-metallic behavior with 100% spin polarization. As the Hubbard is added, the electronic properties show an electronic phase transition from half-metallic to metallic behavior with 68% spin polarization. While the thermal and mechanical properties show very small changes, confirming that the studied compound is mechanically and dynamically stable. • CoMnTe compound is more stable in γ -phase with the ferromagnetic configuration. • CoMnTe compound is mechanically and thermodynamically stable. • CoMnTe compound is promising for spintronic applications. [ABSTRACT FROM AUTHOR]

The electronic and transport properties of a series of covalently functionalized graphene sheets m (FeBz) n -G (m , n = 1, 2) are calculated by density functional theory (DFT) and the nonequilibrium Green's function (NEGF) methods. All the studied systems are chemically stable due to the d – π interaction between Fe and graphene. Addition of (FeBz) n (n = 1, 2) introduces a half-metallic behavior: the up-spin state degradates into a semiconductor channel while the down-spin state behaves as a metallic channel. Particularly, two-fold anisotropy magnetism could be obtained, with the ferromagnetic ordering extending either parallel to the graphene plane originated from the Fe- d up-spin state or perpendicular due to the d -electron coupling along the Fe-Bz-Fe-Bz chain in the down-spin state. Because of the trapping effect, attaching (FeBz) n decreases the conductivity. Anisotropy inherited from graphene after functionalized with (FeBz) n (n = 1, 2): zigzag direction has higher conductivity than armchair direction. The number and alignment style of (FeBz) n (n = 1, 2), and the spin-polarized character, all have impacts on the transport property. Our findings provide useful guidelines for achieving graphene-based electronic and spintronic nanodevices by attaching other similar long multi-decker metal-arene systems. [Display omitted] • Electronic and transport properties of functionalized graphene m (FeBz) n -G (m , n = 1, 2) are calculated theoretically. • Addition of (FeBz) n (n = 1, 2) introduces half-metallic behavior. • Ferromagnetic ordering extends not only parallel to the graphene plane but perpendicular to it. • Conductivity is determined by anisotropy inherited from graphene, number and alignment of (FeBz) n , and spin polarization. [ABSTRACT FROM AUTHOR]

The spin resolved electronic transport behavior of ZnO nanowires (ZnONWs) linked to electrodes is investigated using first principles calculations within Density Functional Theory incorporating the Hubbard (U) term. A defect (resulting from Zn vacancy) in ZnO, as well as the use of Ni electrodes, have a significant influence on the electronic structure properties. They improve the magnetic moment of the system and generate a spin-asymmetric spectra. The ZnONWs linked to the Ni electrodes are probed for spin resolved differential conductance and current. Although the spin down differential conductance curves have a similar trend, the variations in spin up conductance are dissimilar. ZnONW-based devices appear promising for prospective spintronic applications due to their nearly half-metallic behavior around the Fermi energy and acceptable spin polarization in current. • ZnO nanowires are promising for spintronic applications. • The magnetism in ZnO nanowire-based devices can be enhanced using a vacancy and/or Ni electrodes. • Spin polarization in current and DOS is appreciable. [ABSTRACT FROM AUTHOR]

This work presents a theoretical investigation on the electronic properties of double atomic carbon chains bridging graphene electrodes with density functional theory in combination with non-equilibrium Green's function. The influence of strain on the conductance of atomic carbon chains is significant. However, the coupling effect between adjacent chains dominates the intrinsic transport of double atomic carbon chains. For the coupled double atomic chains, the electron conductance of even-numbered atomic chains is significantly enhanced, while the electron conductance of odd-numbered atomic chains decreases to a certain degree, and the dependence of the conductance of double atomic chains on electrode configuration is stronger than the corresponding single atomic chain. More intriguingly, the coupled double atomic chains exhibit excellent spin-filtering properties with antiparallel spins on two electrodes. The current spin polarization stems from the coupling-induced changes of electron density and band offset reaches 100%. The coupled double atomic carbon chains have great potential application in spintronic devices and carbon-based field-effect transistors. • Coupling of carbon atomic chains increase the average conductance of atomic chains. • Coupling of carbon atomic chains induces very strong spin filter effect, even reaches 100%. • MR ratios of double carbon atomic chains increase by up to 5 orders of magnitude of the single carbon atomic chain. [ABSTRACT FROM AUTHOR]

Full potential linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT) is used to investigate the structural, electronic, magnetic and optical properties of nonstoichiometric fluoroperovskite compounds Sr 1 − x Eu x LiF 3. The Nonstoichiometric systems characterized by new physical properties are compared with the theoretically investigated cubic fluoroperovskite SrLiF 3. The modified Becke–Johnson (mBJ) exchange potential is used to calculate the band gap energy E g. The nonstoichiometric systems show spin dependent band gap characterized by very large magnetic moment in Eu sites. • Cubic fluoroperovskite SrLiF 3 shows large direct band gap (Γ−Γ). • These compounds show half metallicity behaviour in the minority density of states. • The optical properties indicate that the nonstoichiometric Sr 1−x Eu x LiF 3 compounds are assumed as light harvesters, since the Eu+2 doping increases the absorption. [ABSTRACT FROM AUTHOR]

Highlights • The spin polarization of hybrid interface states is manipulated by selecting anchoring groups with different types of outer orbitals and atomic electronegativity. • A dependence of the interfacial spin polarization on the atomic electronegativity is revealed. • Significant enhancements of the tunneling magnetoresistance and spin filtering efficiency are realized by using the anchoring atoms with large electronegativity. Abstract Based on density functional theory combined with nonequilibrium Green's function method, the spin polarization of hybrid interface states in magnetic molecular junctions and their roles in spin-dependent transport are investigated. The results demonstrate that by choosing anchoring atoms with different types of outer orbitals, the spin polarization of the hybrid interface states can be tuned. A dependence of the spin polarization on the atomic electronegativity is revealed, where a high spin polarization is achieved in the case of O atom with large electronegativity. The transport calculation shows that a corresponding adjustable spin-dependent transport is realized, where an enhanced tunneling magnetoresistance and a large spin filtering efficiency are realized by using the anchoring atoms with large electronegativity. This work proposes a valid way to enhance the functionality of molecular spintronic devices by manipulating the hybrid interface states. [ABSTRACT FROM AUTHOR]

Abstract The Co-Ta system has been reviewed and the thermodynamic description was re-assessed in the present work. DFT (density functional theory) calculations considering spin polarization were performed to obtain the energies for all end-member configurations of the C14, C15, C36 and μ phases for the evaluation of the Gibbs energies of these phases. The phase diagram calculated with the present description agrees well with the experimental and theoretical data. Considering the DFT results was essential for giving a better description of the μ phase at lower temperatures. [ABSTRACT FROM AUTHOR]

Abstract We calculate the temperature dependent spin-polarized transport properties of ferromagnetic vanadium ditelluride (VTe 2) single layer by using density functional theory (DFT) along with non-equilibrium Green's function (NEGF) formulation. The spin-dependent current and transmission spectrum are calculated to explain the spin filtration effect based on temperature and excellent spin Seebeck effect. A high value of Spin polarisation efficiency ∼100% is achieved at a lower value of temperature difference range. Due to the high-temperature difference between the left electrode (T L) and right electrode (T R) lower Spin polarisation efficiency is obtained. A thermal giant magneto resistance of ∼1.5 × 103% is obtained and it increases with increase in temperature difference between the left and right electrode (ΔT), and it also depends on T L. The excellent characteristics such as high MR and perfect spin polarisation makes VTe 2 a prominent material for spin caloritronic applications. Highlights • Temperature dependent spin Seebeck and spin filtration effect is observed in VTe 2. • Thermal GMR increases with increase in electrode temperature difference (ΔT). • Higher spin polarisation efficiency at lower ΔT and vice-versa. [ABSTRACT FROM AUTHOR]

The thermoelectric properties (TE) of rare-earth based RENi 2 (RE = Dy, Ho and Er) Laves phase compounds, have been investigated using first-principle density functional theory. The generalized gradient approximation (GGA) and local spin density approximation (LSDA) with Hubbard parameter (U) have been used for exchange and correlation effect. Calculated ground state properties such as lattice constants are in good agreement with pervious reported results. The electronic band structures display the metallic nature of these compounds. The high values of N(E F ) are responsible for more metallic nature in spin down channel as compared to spin up channel. The electrical conductivity (σ/τ) decreases with increasing temperature. The negative value of Seebeck coefficient indicates that electrons play major role in spin up profiles but in spin down profiles both type of charge carriers are contribute for Seebeck effect. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The full Heusler alloy (Fe 2 CoSn) nanowires are formed using AC electrodeposition in AAO templates. • The SEM images have confirmed the average diameter and length of nanowires 40–60 nm and 15 μm respectively. • The M-H loops show the variation of coercivity and saturation magnetization with respect to deposition potential. • The half-metallicity, band gap and 100% spin polarization was also confirmed using density functional theory (DFT). Abstract Fe 2 CoSn Heusler alloy nanowires (NWs) were synthesized for the first time through alternating current (A.C) electrodeposition due to its manufacturing and size tailoring ease. To approach our desired goal, deposition potential was used to control the alloy composition of Fe, Co and Sn contents as it was almost inversely proportional to the composition ratio of Sn and (Fe, Co). The effects of deposition potential on morphology, chemical composition, crystal structure and electric/magnetic properties were investigated. According to the scanning electron microscopy (SEM) micrographs, the Fe 2 CoSn NWs exhibited diameter of about 40–60 nm range and the length existing in the range of 15 µm. X-ray diffraction (XRD) patterns reveal that two types of reflection were observed i.e. fundamental (A2-type crystal structure) and super-lattice (L2 1 crystal structure) reflection. Almost 35 nm was the average grain size calculated through XRD technique using full width half maximum (FWHM). The composition of Fe 2 CoSn nanowires has been confirmed by using EDX analysis, whereas surface chemistry of Heusler alloy (Fe 2 CoSn) NWs was examined through FTIR. Magnetic measurement indicated that Fe 2 CoSn Heusler alloy was ferromagnetic at room temperature with a maximum coercivity of 484 Oe at 17 V. Two probe (I-V) curve showed non-ohmic character and Hall measurement (Four probe) revealed the inverse relation between resistivity (ρ), mobility (µ) and followed excellent transport as well as spin dependent properties of Heusler alloy (Fe 2 CoSn) NWs. Half metallicity in (Fe 2 CoSn) Heusler alloy NWs was confirmed by full potential lineralized augmented plane wave methods (FP-LAPW) within density functional theory (DFT) in detail. These results revealed that Heusler alloy (Fe 2 CoSn) NWs have wide range of multifunctional properties such as combination of magnetism and exceptional transport properties in spintronic devices. [ABSTRACT FROM AUTHOR]

Spin-polarized density functional theory is used to investigate the formation energetics and magnetic properties of Ca/transition metal TM (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) doped CaZrO 3 systems. A strong interdependence of formation energy and TM dopant size (ionic radii) is evident, which increases solely with the increase of dopant atomic number. Our results elucidate that Co@Zr, Cr@Zr, Fe@Zr, and V@Zr doped systems show half-metallic nature due to partial filling of d -orbitals with a reasonable charge carrier density of ∼10 21  cm −3 , while Ca@Zr and Cu@Zr doped systems exhibit p -type ferromagnetism because of deficiency of electrons. In contrast, Sc-dopant reveals as p -type non-magnetic due to strong hybridization. Furthermore, Ti@Zr, Mn@Zr, and Ni@Zr doped CaZrO 3 systems, depict non-magnetic behavior. Interestingly, Mn@Zr doped system contains high magnetic moment of 3 μ B and show insulating nature. The findings of present calculations yield a wide avenue for practical applications of these doped systems in spintronics. [ABSTRACT FROM AUTHOR]

Spin-polarized, first-principles total energy calculations have been performed to investigate the structural, electronic and magnetic properties of the chromium nitride (0 0 1) surface. Different approximations were used to treat the non-classical exchange correlation energy: LDA, GGA, LDA + U (3 eV ≤ U ≤ 5 eV) and GGA + U (1 eV ≤ U ≤ 4 eV). It was found that LDA + U with U = 4 eV describes correctly the structural, electronic and magnetic properties of bulk CrN. The CrN (0 0 1) surface has been investigated, employing the surface formation energy (SFE) formalism. For the surface in the cubic phase, three different structures were found to be stable: an ideally terminated surface, one with no nitrogen atoms in the second layer, and one with half of the nitrogen atoms missing in the second layer. In the case of the orthorhombic surface, only the ideal surface is stable in all the range of the chemical potential. Density of States (DOS) calculations show a metallic behavior for all the stable surface structures, with the main contribution around the Fermi level coming from Cr-d orbitals. The effect of nitrogen vacancies is clearly observed with an increase in the metallic behavior in the structures having less nitrogen atoms. [ABSTRACT FROM AUTHOR]

Searching experimental feasible two-dimensional (2D) ferromagnetic crystals with room-temperature magnetic order and high spin-polarization is one key for the development of next-generation spintronic devices. Inspired by the recent experimental achievement for the synthesis of Janus MoSSe monolayer with out-of-plane symmetry, here, by ab initio calculation, we demonstrate this feasibility with the discovery of intrinsic 2D ferromagnetic Janus TMDs monolayer (TMXX′, TM = V, Cr and Mn; X, X′ = S, Se and Te, X ≠ X′) with large spin-polarization and high Curie temperature. Particularly, the MnSSe monolayer show half-metal with 100% spin polarization and wide half-metallic gap. A Curie temperature as high as 400 K has been found for VSSe materials. The formation energy calculation for Janus TMDs can be comparable with the TMDs monolayer. The dynamical stability for these 2D crystals also have been confirmed by phonon spectrum calculation. Our study presents a new class of 2D magnetic materials for future spintronics and valleytronics. [ABSTRACT FROM AUTHOR]

The graphane can realizes a perfect spin filtering by changing the hybridizations of the defective carbon atoms. The H-vacancy defects introduce a novel transport channel in the two-probe σ-bond graphane devices, providing by through-space interactions. [Display omitted] The electronic transport properties of H-vacancy-defected graphane are investigated by using the density functional theory (DFT) and Non-equilibrium Green's Function (NEGF) methods. Results show that the band gap of graphane depends on the relative positions of the defect bands introduced by H vacancies and the valence or conduction bands, suggesting the band gap controllability. The defect bands are obviously spin polarized and the ratio is almost 100%. And the magnetization of the system can be tuned by defect concentration and location. Moreover, in the two-probe systems, the presence of H-vacancy-defect bands near the E f plays an important role in controlling spin-dependent transport of graphane. A perfect spin-filtering effect with 100% spin polarization could be realized by H-vacancy defects. The spin properties indicate the potential of graphane as an option for future graphene-based spin filters and spintronic devices. [ABSTRACT FROM AUTHOR]

Here, the spin transport properties of molecular devices comprised of a transition metal-dibenzotetraaza[14]annulene complex (TM-DBTAA, TM=Co, Cu, Ni) connected to two single-walled carbon nanotube (SWCNT) electrodes have been theoretically investigated by using the first-principles method. In addition, the effect of O 2 adsorption on the TM atom on the spin transport properties of the investigated devices is inspected. The calculations reveal that Co-DBTAA behaves as a spin filter with SFE close to 100%. Upon O 2 adsorption, the spin polarization of the current for Co-DBTAA is changed from spin-down to spin-up with the magnitude of SFE nearly unchanged. More interestingly, for the spin non-polarized and nonconducting Ni-DBTAA, the adsorption of an O 2 molecule induces a spin-up polarized current with remarkable SFE larger than 90%. This work is helpful for future designing of molecular spin filters as well as gas sensors. • Co-DBTAA has a spin filtering efficiency close to 100%. • The polarization of spin filtering in Co-DBTAA is reversed by oxygen adsorption. • Ni-DBTAA is spin non-polarized and nonconducting. • Oxygen adsorption induces a large spin filtering efficiency in Ni-DBTAA. [ABSTRACT FROM AUTHOR]

First-principles calculations, were carried out to study the structural stability of the cubic [ (F m 3 ‾ m) , (F 4 ‾ 3 m) ] and tetragonal [ (I 4 / m m m) , (I 4 ‾ m 2) ] phases, of R u 2 V Z (S i ; G e) full Heusler compounds; where Energy of formation, elastic, Mechanical, phonon and thermodynamic properties and electronic density of states were determined. Through our results, all ferromagnetic phases exhibit a total magnetic moment of 1 μ B for both R u 2 V S i and R u 2 V G e compounds, except the tetragonal (I 4 ‾ m 2) phase that manifest a zero ( 0 μ B) total magnetic moment.Further, the antiferromagnetic state of the cubic phase F m 3 ‾ m R u 2 V Z (S i ; G e) was found energetically more favorable than the ferromagnetic one.The analysis of the calculated elastic and dynamic properties, revealed that only the regular cubic phase (F m 3 ‾ m) of the R u 2 V S i and the regular tetragonal phase (I 4 / m m m) of the R u 2 V G e are the most stable among the considered phases. The calculated electronic density of states for the ferromagnetic stable phases, confirm the existence of a half-metal character with high spin polarization (P n) of: ∼ 91 % and ∼ 100 % for the R u 2 V S i and R u 2 V G e respectively. • In This article applied the Full full-potential linearized augmented-plane-wave method (FP-LAPW) to the determination of the structural, dynamic mechanical and electronic properties of the two full Heusler compounds R u 2 V S i and R u 2 V G e. • The antiferromagnetic state for the cubic (F m 3 ‾ m) R u 2 V Z (S i ; G e) compounds was found more favorable than the ferromagnetic one. • The analysis of the calculated elastic and dynamic properties, show that only the regular cubic phase (F m 3 ‾ m)) of the R u 2 V S i and the regular tetragonal phase (I 4 / m m m) of the R u 2 V G e are the most stable among the considered phases. • The electronic density of states for the ferromagnetic stable phases, confirm the half-metal character with high spin polarization for the R u 2 V S i and R u 2 V G e respectively. [ABSTRACT FROM AUTHOR]

The possibilities of ferromagnetism induced by nonmagnetic dopants (Cu, Zn) in double perovskite S r 2 A l T a O 6 at B sites are investigated by density functional theory. Calculations reveal that substitutions at Ta-site tend to form high spin electronic configurations and could induce ferromagnetism which can be attributed to the hole-mediated p - d hybridization between Cu (or Zn) e g states and the neighboring O 2p states. The dopants preferably substitute at Al-site and adopt low spin electronic structures. Due to the smaller hole concentration and weaker covalent intensity, S r 2 A l T a O 6 with dopants at Al-site exhibits p -type metallic semiconductors without spin polarization. [ABSTRACT FROM AUTHOR]

The electronic, magnetic and optical properties of C- and N-doped CeO 2 bulk and (111) surface have been systematically investigated by first-principles calculations. The results show that the spin splitting occurs when doping atoms replace the anion sites in the CeO 2 matrix, causing a local magnetic moment of 2.00, and 1.00 μ B for C- and N-doping, respectively. The strong hybridization between dopants 2 p and O 2 p triplet-states around the Fermi level gives rise to the half-metallic character for doped bulk systems, while substitution onto the surface eliminates the degeneration of dopants 2 p orbitals, which results in anisotropic spin atmosphere. Especially, owing to the low formation energy and available RTFM, N-doped CeO 2 would be easily realized in the experiment and should also be wonderful candidate materials for oxide spintronics. In addition, compared with N-doped CeO 2 , the calculated optical properties reveal that C-doped CeO 2 (111) surface is able to enhance the absorption of the visible light. [ABSTRACT FROM AUTHOR]

Using first principles study, through Density Functional Theory combined with Non Equilibrium Green's Function Formalism, electronic properties of endohedral N@C 20 fullerene molecule joining Au electrodes (Au-N@C 20 ) was addressed in the presence of spin property. The electronic transport behavior across the Au-N@C 20 molecular junction was investigated by spin resolved transmission, density of states, molecular orbitals, differential conductance and current-voltage ( I-V ) characteristics. Spin asymmetric variation was clearly observed in the results due to single N atom encapsulated in the C 20 fullerene cage, where the N atom played an essential role in the electronic behavior of Au-N@C 20 . This N@C 20 based molecular bridge, exhibiting a spin dependent I-V variation, revealed a metallic behavior within the bias range from −1 V to 1 V. The induced magnetic moment, spin polarization and other relevant quantities associated with the spin resolved transport were elucidated. [ABSTRACT FROM AUTHOR]

First principles calculations are used to study the spin polarization properties of benzene molecule adsorbed on the graphene surface which doped with transition metals including Mn, Cr, Fe, Co, and Ni. The densities of states (DOS) of the benzene molecule can be induced to be spin split at the Fermi level only when it is adsorbed on Mn-, and Cr-doped graphene. The p-orbital of the benzene molecule will interact with the d orbital of the doped atoms, which will generate new spin coupling states and lead to obvious spin polarization of the benzene molecule. The spin-polarized density distributions as well as the differential charge density distributions of the systems also suggest that Mn-doped graphene will induce bigger spin polarization than that of Cr-doped graphene. Benzene molecule could be spin-polarized when it is adsorbed on the graphene surface with transition metal dopants, which could be a new method for researching graphene-based organic spintronic devices. [ABSTRACT FROM AUTHOR]

It has been suggested in literature that defects in graphene (e.g. absorbed atoms and vacancies) may induce magnetizations due to unpaired electrons. The nature of magnetism, i.e. ferromagnetic or anti-ferromagnetic, is dependent on a number of structural factors including locations of magnetic moments and lattice symmetry. In the present work we investigated the influence of a relaxed single atom vacancy in garphnene on magnetization which were obtained under different pinning boundary conditions, aiming to achieve a better understanding of the magnetic behaviors of graphene. Through first principles calculations, we found that major spin polarizations occur on atoms that deviate slightly from their original lattice positions, and pinning boundaries could also affect the relaxed positions of atoms and determine which atom(s) would become the main source(s) of total spin polarizations and magnetic moments. When the pinning boundary condition is free, a special non-magnetic and semi-conductive structure may be obtained, suggesting that magnetization should more readily occur under pinning boundary conditions. [ABSTRACT FROM AUTHOR]

The geometrical, electronic and optical properties of Cu or/and N (co)doped TiO 2 /g-C 3 N 4 heterostructure systems have been investigated systematically on the basis of spin-polarized density functional theory calculations. Our calculated results indicate that the band gap of TiO 2 /g-C 3 N 4 heterostructure has an obvious narrowing compared with pure TiO 2 (1 0 1) surface, and (Cu, N) codoping can induce some impurity states of N 2 p and hybridized states of Cu 3 d and N 2 p appearing in the forbidden gap of TiO 2 /g-C 3 N 4 heterostructure, which lead to a decrease of the photon excitation energy and an obvious redshift of the optical absorption edge. Moreover, the charge density difference calculations of Cu or/and N (co)doped TiO 2 /g-C 3 N 4 heterostructure systems show that the excited electrons and holes will eventually accumulate in (co)doping TiO 2 (1 0 1) surface and g-C 3 N 4 monolayer, respectively, which can effectively reduce the recombination of the photogenerated electron-hole pairs by the interfacial coupling of between TiO 2 (1 0 1) surface and g-C 3 N 4 monolayer. This work not only investigates systematically the electronic and optical properties of Cu or/and N (co)doped TiO 2 /g-C 3 N 4 heterostructure, but also suggests that (Cu, N) codoped TiO 2 /g-C 3 N 4 heterostructure is a preferable visible-light photocatalyst. [ABSTRACT FROM AUTHOR]

Co 2 CrAl/GaAs slabs have been constructed to study the electronic structure and magnetic properties by Structeditor program implemented in WIEN2k Code. GGA and LDA parameterizations have been used for exchange correlation functions. The density of states, structure and magnetic parameters have been studied and analyzed. Co 2 CrAl/GaAs (1 1 1) surface shows 80% spin polarization within LDA parameterizations. Variation in spin polarization with varying projections is observed due to different surface terminations and bond length. Effect of capping layers of Au and Cu on the magnetic moment and spin polarization of Co 2 CrAl/GaAs for different surface projections has been studied. The DOS indicates that the spin polarization has enhanced for all surface projections within the GGA approximation for both capping layers. The magnetic moment also varies from the bulk value of 3µ B in Co 2 CrAl/GaAs surfaces. [ABSTRACT FROM AUTHOR]

Using the first-principles periodic boundary density functional theory along with the Grimme function, this study investigated the vacancy formation in the neck area of a 3-D pillared graphene structure. Three different possible configurations of the monovacancy defect formation were studied on a 3-D pillared graphene in order to explore the role of the monovacancy defect in the structural, electronic, and magnetic properties of each configuration. The density of state (DOS), projected DOS and spin polarization of the defected structures were calculated in order to determine which monovacancy site could have a significant impact on the magnetization of the 3-D pillared graphene. The obtained results at the GGA/revPBE level with a DZP basis set revealed that the influence of changing the position of the monovacancy defects from the graphene sheet to the nanotube part of the 3-D pillared graphene could give rise to greater magnetization. In particular, the monovacancy defects on the graphene (sheet) and nanotube (pillar) parts of the 3-D pillared graphene yielded less magnetization and greater magnetization, respectively. Moreover, the simulation results indicated that the px and pz orbitals had a substantial contribution to the spin polarization in these structures. [ABSTRACT FROM AUTHOR]

The magnetic, electric and optical properties of BiFe 0.875 Cr 0.125 O 3 (BFCO) doped with aliovalent ions (Na + , Mg 2+ ) and isovalent ion (Al 3+ ) are investigated by the first principle spin-polarized density functional theory calculations. It is demonstrated that the substitution of M (M = Na + , Mg 2+ , Al 3+ ) for Fe can produce net magnetic moments of 3.0, 2.0 and 3.0 μB, respectively. Besides, Na + doped BFCO exhibits metallicity while Mg 2+ doped system behaves as half-metallicity. Systematic study of electronic structures show that this conversion from semiconductor (BFCO) to half-metal or metal is mainly attributed to the shifting of O 2p, Bi 6s, and Cr 3d states induced by doping with aliovalent Na + or Mg 2+ . Furthermore, the aliovalent ions doped samples express high static dielectric constants of 12.08, 29.44, large refractive indexs of 5.41, 3.46 and both their absorption edges near zero, suggesting advanced optical response in visible region of the doped samples. [ABSTRACT FROM AUTHOR]

Water adsorption on the CuO(111) surface at different coverage has been systematically studied by spin-polarized density functional theory calculations (GGA+U) and atomic thermodynamics. Both molecular and dissociative adsorptions are studied. It is found that H 2 O molecule can chirally adsorb on CuO(111) surface which maybe play an important role in catalysis field. Molecular H 2 O adsorption is preferred for one H 2 O molecule, while mixed molecular and dissociative coadsorption is preferred on CuO(111) surface for two, three and four H 2 O molecules. Molecular and dissociative H 2 O adsorption can coexist at high temperature by using Boltzmann statistics. The phase diagram shows that only three surface configurations are stable thermodynamically: clean CuO(111) surface, two H 2 O and four H 2 O adsorption. The surface uncoordinated copper and oxygen atoms, and hydrogen bonding contribute to the adsorption energies. H 2 O adsorption mechanism has been analyzed by projected density of states (PDOS). [ABSTRACT FROM AUTHOR]

The mechanical, structural, electronic and magnetic properties of s -triazine sheet ( C 6 N 6 ) with embedded Mn atom ( Mn – C 6 N 6 ) is investigated under the influence of external environment (symmetric deformation and perpendicular electric field) using density-functional theory (DFT) with the spin polarized generalized gradient approximation (GGA) and Hubbard U correction ( GGA + U ). Our results show that Mn – C 6 N 6 system is structurally and mechanically stable. The binding energy of Mn embedded in C 6 N 6 sheet can be modulated under the influence of external environment. Moreover, the semiconducting and magnetic properties of the Mn – C 6 N 6 systems under external fields are preserved. We also explore the geometries, electronic and magnetic properties of Mn – C 6 N 6 with adsorbed atoms and molecules. The Mn – C 6 N 6 with adsorbed O atom and O 2 molecule systems shows half-metallic character whereas the remaining systems preserve their semiconducting property. The total magnetic moment per unit cell in most of the systems is found to reduce as compared to that of the Mn – C 6 N 6 sheet. The reduction in the magnetic moment can be related to the strong interactions among the Mn atom and the surrounding atoms which lead to the formation of low-spin configurations. Overall, our results indicate that the Mn – C 6 N 6 systems with and without adsorbed atoms and molecules can serve as potential candidates for future spintronics and catalysis applications. [ABSTRACT FROM AUTHOR]

We report a thorough comparison between the spin-unrestricted semi-empirical molecular orbital (SE-UMO) and density functional theory (UDFT) calculations for a variety of π-conjugated diradical molecules which exhibit through-bond magnetic exchange interactions. The spin-unrestricted neglect of diatomic differential overlap (NDDO)-based methods (UPM6 and UrPM6) and self-consistent charge density functional tight-biding (UDFTB) are examined. The UCAM-B3LYP method is used as a representative of UDFT. We have found that NDDO-based and UDFTB methods give different performances with respect to the results of UCAM-B3LYP. The degree of diradical character in the target systems decreases in the order of UPM6 > UrPM6 ≈ UCAM-B3LYP > UDFTB. The conventional UPM6 and UDFTB calculations tend to overestimate and underestimate the diradical character, respectively, whereas UrPM6 is able to provide much the same results as UCAM-B3LYP. This is convincing evidence that UrPM6 will be useful for in silico screening of materials science at much lower computational cost. [ABSTRACT FROM AUTHOR]

The discovery of different two-dimensional (2D) materials both theoretically and experimentally, can change the scenario of the current electronic industry because of their intriguing properties. Among the 2D materials, the first one which was discovered experimentally was graphene. In this work we have studied the electronic and magnetic properties of a new allotrope of disordered graphene, which is not hexagonal, rather possesses tetragonal symmetry known as T-graphene (TG). Density functional theory (DFT) has been thoroughly employed to study the relevant electronic properties. In previous works, it has been reported that pristine TG is non-magnetic. It is also known that, introducing transition metal (TM) atoms is a feasible way to control the electronic and magnetic properties. Here we have reported the relevant properties of four TM atoms i.e. Sc, V, Cr and Mn doped TG. From the defect formation energy study, it has been noticed that all the structures are endothermic in nature. For each case, we have found appreciable amount of magnetic moment. With increasing atomic weight of the dopant atom, the magnitude of the magnetic moment also increases. We have tried to explain this magnetic ordering with the help of spin-polarized partial density of states (PDOS). Controlling spin degrees of freedom is important for building spintronic devices. From that point of view, we hope this study will be useful to build TG based spintronic devices. [ABSTRACT FROM AUTHOR]

First principles investigations are performed on understanding the spin-polarized transport in carbon nanotubes and carbon nanotube bundles consisting of ( 8 , 0 ) and ( 17 , 0 ) SWCNTs kept in vertical (out-of-plane) arrangement and contacted by two CrO 2 Half-Metallic-Ferromagnetic (HMF) electrodes. On comparison of the results for all the structures, it is observed that carbon nanotube bundle consisting of ( 17 , 0 ) CNT offers high TMR ∼100% and the transport phenomenon is tunneling, since there are no transmission states near Fermi level. However, in individual ( 8 , 0 ) and ( 17 , 0 ) CNT the transport is not because of tunneling, since there are significant number of transmission states near Fermi level. High Magneto Resistance (MR) 96% and 99% is observed in individual ( 8 , 0 ) and ( 17 , 0 ) CNTs respectively. Both TMR and Spin Injection Efficiency η (Spin-Filtration) are higher in ( 17 , 0 ) carbon nanotube bundle structure, which is due to carbon nanotube bundle acting as a perfect barrier in vertical (out-of-plane) arrangement resulting in negligible spin-down current ( I ↓) in both Parallel Configuration (PC) and Antiparallel Configuration (APC). [ABSTRACT FROM AUTHOR]

Induced spin polarization of π-conjugated carbon and h -BN low dimensional fragments at the interfaces formed by deposition of pentacene molecule and narrow zigzag graphene and h -BN nanoribbons on MnO 2 -terminated LSMO(001) thin film was studied using GGA PBE+U PAW D3-corrected approach. Induced spin polarization of π-conjugated low-dimensional fragments is caused by direct exchange with Mn ions of LSMO(001) MnO-derived surface. Due to direct exchange, the pentacene molecule changes its diamagnetic narrow-band gap semiconducting nature to the ferromagnetic semiconducting state with 0.15 eV energy shift between spin-up and spin-down valence bands and total magnetic moment of 0.11 μ B . Direct exchange converts graphene nanoribbon to 100% spin-polarized half-metal with large amplitude of spin-up electronic density at the Fermi level. The direct exchange narrows the h -BN nanoribbon band gap from 4.04 to 1.72 eV in spin-up channel and converts the h -BN ribbon semiconducting diamagnetic nature to a semiconducting magnetic one. The electronic structure calculations demonstrate a possibility to control the spin properties of low-dimensional π-conjugated carbon and h -BN fragments by direct exchange with MnO-derived LSMO(001) surface for spin-related applications. [ABSTRACT FROM AUTHOR]

Using first principles total energy calculations within the periodic spin polarized density functional theory, we have investigated the structural, electronic, and magnetic properties of manganese gallium (MnGa) alloys. Specifically, we explore the MnGa(111)-1 × 2 and 2 × 2 reconstructions. The surface formation energies reveal that selected substitutions occur under Mn (Ga) rich growth conditions. Structures with top layers missing all Mn (Ga) atoms and two layers deep substitutions are also investigated. However, the formation energy shows that these structures are less favorable. For the stable structures, the magnetic properties per layer are proportional to the Mn:Ga ratio. Also, the density of states shows that the MnGa surfaces are metallic. The projected density of states shows that the electronic states in the vicinity of the Fermi level are due mainly to the manganese 3d orbitals. However charge density plots reveal that Mn 3d electrons are closer to the nucleus than Ga sp electrons. Consequently, experimental scanning tunneling microscopy images reveal periodically-arranged bright features, corresponding to the Ga atoms. [ABSTRACT FROM AUTHOR]

Based on non-equilibrium Green's function and density functional theory, a first-principles study of the spin-polarized transport properties and magnetism of 1,3-dimethylpropynylidene molecule sandwiched in two Ag electrodes is performed. Strong spin-polarized negative differential resistance and spin filtration effect are present. We also find that the net spin moments of molecular magnet abnormally decrease driven by electric field because the molecular orbitals around Fermi level have opposite spin direction and that non-spin-polarized electrical read out of spin states for single molecular magnets is possible. [ABSTRACT FROM AUTHOR]

The interfacial interaction between graphene and ferromagnetic substrate is known to bring additional controls to the intrinsic properties of graphene, in addition to inducing some novel properties to the system which may have potential application in spintronics. In this work the spin-polarized electronic structures across the graphene–ferromagnet interface has been investigated using first principles density functional theory calculation as it is implemented on Vienna ab-initio simulation package (VASP). The electronic and magnetic properties of the interface have also been investigated. The ferromagnet substrate was represented by N i (111) and C o (111) surfaces due to their structural resemblance to graphene. The study reveals that the ferromagnet layers adjacent to the interface show a transition of spin orientation from in plane to out of plane. The critical thickness of the slab which yields the maximum shifting of the spin orientation of the ferromagnet layers is also determined. The strong hybridization between different orbitals of graphene and ferromagnet significantly affects the electronic and magnetic properties of the interface. Reduction on the local magnetic moments of the ferromagnet layers adjacent to the interface and the induced spin polarization on the graphene layer were also observed which is due to the impacts of the hybridization. This work will provide important information which can be used for efficient design of interfaces for graphene-based spintronics. [ABSTRACT FROM AUTHOR]

This work reports an experimental and theoretical investigation of pure, Sr, and (Sr,Co) co-doped CdS systems. Pure and co-doped CdS nanostructure thin films were grown with varying Co doping concentrations by sol-gel spin coating method. X-ray diffractograms of the films reveal that the films grow along (002) plane and the crystallites sizes were about ∼3–6 nm. The band gaps of the films were obtained in order of 2.30–2.48 eV and a blue shift in the band gap with co-doping was observed in comparison with Sr:CdS system. In addition, pure and co-doped CdS system were also investigated via density functional theory. Initially, pure and co-doped CdS systems were optimized using WIEN2k software based on density functional theory. The calculated optical properties and band gap reveal a close agreement with the experimental results. The (Sr,Co) co-doped CdS shows the spin polarization effect on the valence band which makes this materials suitable for optoelectronics and spintronics applications. [ABSTRACT FROM AUTHOR]

The density of state maps and simulated photoelectron spectra of the lowest energy structure of La 2 Ge 6 - which represents extremely inconspicuous spin polarization. [Display omitted] • Three exchange–correlation functionals are used for accuracy and consistency of geometry optimization. • The dopant atoms are basically located at the vertex top of bipyramid. • For different Ln element doping, the enhancement effect on clusters stability is Ce/ La > Lu > Yb. • Ln 2 Ge 6 - (Ln = La, Ce, Yb, Lu) clusters represent extremely inconspicuous spin polarization. The influence of double lanthanide metal atoms on the stability of germanium-based clusters was conducted by means of density functional theory calculations. The consistency and accuracy of structure optimization are tested with three exchange correlation functionals (PBE, BPW91 and B3LYP). Unlike the pentagonal bipyramid derivatives of LnGe 7 - and pure germanium, the ground state structures of Ln 2 Ge 6 - (Ln = La, Ce and Lu) clusters are preference to tetragonal bipyramid with two capped atoms. The enhancement effect on clusters stability is Ce/ La > Lu > Yb. Total density of states diagram represents the extremely inconspicuous spin polarization of Ln 2 Ge 6 - clusters. In fact, the value of the magnetic moment is also very small, which is 1 μB. [ABSTRACT FROM AUTHOR]

[Display omitted] • The N -doped coralline Co 9 S 8−x N x catalyst possessed filamentous porous structures. • ∼100 % degradation efficiency of AMT was achieved in 120 min. • Electrons redistribution and charge transfer mechanisms of Co 9 S 8−x N x were revealed. Improving the recalcitrant emergent contaminant removal in electron-Fenton (EF) has been one of the focal problems. Here, a N -doped coralline Co 9 S 8−x N x catalyst was synthesized with high electronegativity and strong spin polarization for promoting the H 2 O 2 generation efficiency and Amitriptyline (AMT) removal. After doping nitrogen, catalytic performance of Co 9 S 8−x N x has increased ∼10 % on AMT decay and the treatment time was shortened ∼40 min. Co 9 S 8−x N x induced 2-electron oxygen reduction reaction (ORR) mechanism has also been investigated. According to electronic structure analysis, electrons surrounding the cobalt atoms were redistributed and the π* orbitals of *O 2 were occupied asymmetrically forcing *O 2 to be of radical nature active for hydrogenation, which significantly reduced required absorption energy in the rate-determining step (RDS). This work clarifies the mediate role of N -doped activating delocalized electron of adjacent atoms on the surface of Co 9 S 8−x N x and also gives new insights into the rational design of catalyst for refractory pollutant degradation in wastewater. [ABSTRACT FROM AUTHOR]

• The conformations of SO 3 on the catalyst La 2 CoFeO 6 (0 0 1) is calculated and most stable adsorption structure is found. • Cohesive energy, adsorption energy, bader charge, deformation charge density and density of states are calculated. • Compared with LaCoO 3 , the doping of Fe elements can reduces the adsorption energy and charge trans. • Fe doping can enhance anti-sulfur ability and inhibits the next poisoning reaction. In this paper, the method of spin polarization density functional theory and vasp software package are used to simulate the adsorption of SO 3 molecules on the surface of La 2 CoFeO 6 (0 0 1). Through the optimization of different initial adsorption structures, the adsorption energy is compared, the most stable adsorption method is found, and bader charge and state density analysis are performed. The results show that after the CoO 2 surface is doped with Fe, the most stable adsorption configuration of SO 3 on the surface of CoFeO 4 (0 0 1) is an O-oriented adsorption at the top position of Fe, and the adsorption energy is −2.0366 eV, which is significantly reduced, and the amount of bader charge transfer is also reduced, and the density change and peak of Fe spin (d) state are larger than that of Co spin (d), indicating that the sulfur resistance of perovskites is significantly enhanced. Therefore, this paper will lay a certain theoretical foundation for the study of perovskite anti-poisoning mechanism, and provide a meaningful reference for further experimental research. [ABSTRACT FROM AUTHOR]