Search

[Display omitted] • Chiral-induced spin selectivity effect used for enhancing electrocatalytic properties. • overpotential decreased by 197 mV and there is a three-fold increase in the current density due to the spin effect in the oxygen evolution reaction. • Threefold increase and fourfold decrease in the current density and overpotential respectively for the hydrogen evolution reaction. • The formation of H 2 O 2 is retarded significantly due to the spin effect. • The combination of Al and chiral molecules influences the water-splitting process. The spin-polarized electrons, generated due to the chiral-induced spin selectivity (CISS) effect, play a critical role in enhancing the catalytic behavior during oxygen evolution reaction (OER). In this research, we have designed and investigated the electrocatalytic performance of a chiral bilayer hybrid structure utilizing D-Phenylalanine-coated Ni/Al bilayer thin film. Subsequently, spin-dependent electrochemical measurement reveals that there is a nearly two-fold increase in the spin polarization (of electrons) value to 9 %, when the D-Phenylalanine molecule is anchored onto to Al overlayer of Ni/Al electrodes than on the Ni itself. Accordingly, the overpotential decreased by 197 mV and there is a three-fold increase in the current density value to 39 mAcm−2 in OER for D-Phenylalanine-coated Ni/Al electrodes than that coated on Ni surface. Moreover, the same electrode also demonstrated excellent hydrogen evolution reaction (HER). The faradaic efficiency calculated for the D-Phenylalanine-coated Ni/Al bilayer hybrid structure is 88.7 % and 96 % for OER and HER respectively. This chiral bilayer hybrid architecture presents an innovative way of enhancing the spin polarizability with superior catalytic activity for both OER and HER. [ABSTRACT FROM AUTHOR]

Monolayer SnO has attracted extensive attention due to the unique electronic properties, which have potential applications in nanoelectronic and optoelectronic devices. Transition metal (TM) atoms are often used to modulate electronic structures and magnetic properties of two dimensional (2D) materials, which can facilitate the application of these materials in spintronic devices. The electronic structure and magnetic characteristics of 3 d TM (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) adsorbed SnO monolayer are predicted by first-principle calculations. The n -type doping in the SnO monolayer appears when Sc, Ti, V, Cr, Mn, Fe and Zn atoms are adsorbed. Co, Ni and Cu adsorptions induce the p -type doping in the SnO monolayer. In addition, the magnetic moments of SnO in the adsorption systems are in the range from −0.038 to 0.414 μ B , and that reach the maximum at the case of Ni-absorbed. It is also found that Fe, Co and Ni adsorbed SnO monolayers have a perpendicular magnetic anisotropy (PMA), while Ti, V, Cr and Mn adsorbed SnO monolayers have an in-plane magnetic anisotropy (IMA). Our results indicate that TM adsorbed SnO monolayers have the potential applications in spintronic devices. Unlabelled Image • n -Type doping in SnO monolayers appears when Sc, Ti, V, Cr, Mn, Fe and Zn are adsorbed. • Co, Ni and Cu adsorptions induce the p -type doping in SnO monolayer. • TM atoms adsorption can induce the spin polarization in monolayer SnO. • Fe, Co and Ni adsorbed SnO monolayers show perpendicular magnetic anisotropy. [ABSTRACT FROM AUTHOR]

In this research, high–density La 0.67 (Ca 0.24 Sr 0.09)MnO 3 : x Ag 2 O (LCSMO: x Ag 2 O, x = 0, 0.05, 0.1. 0.15, 0.2, and 0.25) composites were successfully fabricated through the conventional sol-gel method. Scanning electron microscopy (SEM), X–ray photoelectron spectroscopy (XPS) and XRD data confirmed presence of silver at A sites (La3+/Ca2+/Sr2+) as Ag+ and segregates at grain boundaries (GBs) to form metallic silver. The electrical properties greatly improved by adding Ag 2 O. Significant enhancements in peak temperature coefficient of resistivity (TCR) and magnetoresistance (MR) at room–temperature (300 K) were observed for LCSMO: x Ag 2 O composites. The peak TCR increased from 3.7% K−1 (299.3 K, for x = 0) to 14.8% K−1 (301.0 K, for x = 0.2), and MR rose from 16.9% (303.0 K, for x = 0) to 34.1% (300.6 K, for x = 0.2). These improvements in peak TCR were attributed to increased grain size and formation of metallic silver at GBs or within the composites. Moreover, peak MR was higher in Ag 2 O doped composites, which was mainly due to large spin polarization effect and strong coupling ferromagnetic domains under external magnetic field. Overall, the large room-temperature TCR and MR values of LCSMO:0.2Ag 2 O composites look promising for future advanced uncooling infrared bolometers and magnetic sensors. Unlabelled Image • Room-temperature TCR increased from 3.7% K−1 (for LCSMO) to 14.8% K−1 (for LCSMO:0.2Ag 2 O). • Room-temperature MR rose from 16.9% (for LCSMO) to 34.1% (for LCSMO:0.2Ag 2 O). • LCSMO:0.2Ag 2 O composites look promising for uncooling infrared bolometers or magnetic sensors. [ABSTRACT FROM AUTHOR]

The recently predicted penta-RuS 4 monolayer with high stability, large nontrivial band gap and robustness against oxidation is promising for applications in nanoelectronics. The band structure of this material exhibits unique characteristics under the uniaxial strains and we show that this feature provides the possibility of generating the controllable charge and spin beams. We calculate the transport coefficients for the strain barrier in this monolayer, generally, in the presence of a magnetic filed and an applied voltage. Charge transport through the strain barrier shows that we can generate electron beams which their directions are adjusted by the strain and the external voltage. Also, we show that by addition of a magnetic field, we can generate fully spin polarized electron beams, emerging at angles determined by the applied voltage. These features can be of great importance in designing splitters and spin lenses. The possibility of changing the perfect polarizations between the two spin states, easily by altering the voltage, highlights the potential application of RuS 4 monolayer for spintronic switches. Our calculations demonstrate that for the very small lengths of the strain barrier, the tunneling effect of evanescent waves dominates the contributions of the itinerant waves in transport process. We show that this unique phenomenon is related to the shape of the band structure. • Generation of electron beams with directions adjustable by strain and voltage • Easy switch of the perfect spin polarization by altering the voltage • Perfect spin-polarized beams with tunable direction by using a magnetic field • The tunneling effects of the evanescent waves overcome the traveling waves [ABSTRACT FROM AUTHOR]

The density functional theory (DFT) was used to analyze the electron spin competition interaction between next neighbor Ni atoms in various artificially designed structures in a nano-SiC monolayer honeycomb structure. The electronic structural, magnetic and optical properties of a monolayer SiC materials that were doped with different quantities of Ni in a specific shape are detailed in this paper. Interestingly, spin polarization appeared to occur in the structures that were doped with one Ni and 3Ni having a triangular structure. However, there was no spin polarization present in these materials prior to Ni doping, 2Ni doping with a linear structure and 4Ni doping with rhombic structure. The conduction band of the Ni-doped system moved toward the low energy direction which produced a decrease in the band gap. Calculations of the optical properties showed that Ni doping enhanced their photoconduction. It is hoped that the results of this study will have encouraging implications for the application of photoelectric devices and controllable magnetic materials. • Ni structural doping induced spin polarization on the nano-SiC film. • Band gap reduction caused by doping Ni atoms in the system. • There was a frustrated exchange interaction between the next neighboring Ni atoms in the triangle structure. • Optical properties of the doped material showed that Ni doping improved photoconductivity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Spin-polarized field emitter using antiferromagnetic Cr thin film on W(0 0 1) facet. • The maximum spin polarization of 50% at room temperature. • The stable value and direction of spin polarization over 3 h. Abstract To generate high and stable spin-polarized electron beams by field-emission for applications to electron microscopy and spectroscopy, we demonstrated spin-polarized field-emitted electrons from a Cr thin film deposited on W 〈 0 0 1 〉 tips at room temperature without an external magnetic field. A spin polarization of the field-emitted electrons of 35–50% was achieved when the Cr thickness was higher than 20 nm. In addition, a maximum spin polarization of 50% was achieved, consistent with the value for a Cr(0 0 1) surface expected by first-principles calculations. The polarization direction was also stable for 3 h with no abrupt change. This study indicates that antiferromagnetic Cr is proper cathode material for a field emitter than other ferromagnetic materials with an instability limited by superparamagnetic state. [ABSTRACT FROM AUTHOR]

Highlights • Asymmetry spectra determined with Spin Polarized Low Energy Electron Microscopy. • Physics of the observed maxima and minima of the asymmetry spectra. • Observation of spin-dependent surface effect/state in Fe above the vacuum level. • Determination of spin diffusion length in Fe. Abstract The magnetic properties of ultrathin ferromagnetic films are studied by means of Spin Polarized Low Energy Electron Microscopy. Measurements of the onset of ferromagnetic order, distribution and shape of magnetic domains, magnetization direction and their change are now well established standards for this technique. Here, the asymmetry parameter has been determined as a function of film coverage and energy of the incident electron beam. It reveals oscillatory behavior which is usually described as due to the quantum size effect (QSE). We explore the origin of the characteristic features observed in the asymmetry curves and distinguish between the QSE oscillations and other phenomena influencing the shape of the asymmetry curves. As an example we discuss the asymmetry of ultrathin iron films grown on the W(1 1 0) surface. [ABSTRACT FROM AUTHOR]

Highlights • The transmission efficients of Fe 4 N/Ag/Fe 4 N at equilibrium and nonequilibrium are investigated. • The magnetoresistance ratio and spin injection efficient of Fe 4 N/Ag/Fe 4 N at different bias voltages are calculated. • Fe 4 N/Ag/Fe 4 N has a better performance when bias voltage ranges from 0 V to 0.1 V. Abstract Fe 4 N has been confirmed to possess high spin polarization of 81.3% and low Gilbert damping constant of 0.021 ± 0.02 in the recent experiment. To explore the potential applications of Fe 4 N in spintronics devices, the current-perpendicular-to-plane spin valve employing Fe 4 N as electrode and Ag as spacer is simulated to study the spin polarized quantum transport by utilizing the first principles calculations combined with nonequilibrium Green's function. The project density of states (PDOS), transmission coefficient, spin-polarized current, magnetoresistance (MR) ratio and spin injection efficiency (SIE) as a function of bias voltage are studied. Our calculations reveal that spin down electron is the majority spin polarized electron and the absolute value of MR ratio of Fe 4 N/Ag/Fe 4 N at equilibrium reaches up to 174%, and it decreases with the bias increases. Besides, our results indicate that Fe 4 N/Ag/Fe 4 N device has stable SIE value of about 40% and stable MR ratios of about 150% when bias increases from 0 V to 0.1 V, and the device has a better performance within this voltage range. [ABSTRACT FROM AUTHOR]

Structural, electronic and magnetic properties of the chromium (Cr) nanostructure formation on GaAs(1 1 1)–(2 × 2) surfaces are investigated. Studies are performed by first principles total energy calculations within the periodic spin polarized density functional theory plus Hubbard correction (GGA + U) with 1 < U < 5 eV, as developed in the PWscf code of the quantum ESPRESSO package. The chromium adsorption and incorporation into the GaAs(1 1 1)-(2 × 2) atomic structure are investigated on both gallium and arsenic terminated surfaces. Different coverage of Cr is considered from ¼ monolayer (ML) up to a full ML to determine the relaxed configurations and the most favorable structure. High symmetry sites are considered to explore the Cr adsorption and incorporation into the GaAs structure, these are: H3, T4, Top and Bridge. Surface atomic structures contain different number of atoms therefore to determine the most stable atomic geometry the surface formation energies are constructed. On the As terminated surface, under As rich conditions the CrAs bilayer formation is the most favorable structure. On the Ga terminated surface, under Ga rich conditions the Cr trimer formation is the most favorable configuration. Electronic properties of the most stable structures are investigated by calculating the total density of states (DOS) and projected DOS. Results indicate that the most favorable nanostructures exhibit metallic behavior with antiferromagnetic characteristics. [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]

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]

Hydrogen is a green energy carrier with high enthalpy and zero environmental pollution emission characteristics. Photocatalytic hydrogen evolution (HER) is a sustainable and promising way to generate hydrogen. Despite of great achievements in photocatalytic HER research, its efficiency is still limited due to undesirable electron transfer loss, high HER over-potential and low stability of some photocatalysts, which lead to their unsatisfied performance in HER and anti-photocorrosion properties. In recent years, many spintronics works have shown their enhancing effects on photo-catalytic HER. For example, it was reported that spin polarized photo-electrons could result in higher photocurrents and HER turn-over frequency (up to 200%) in photocatalytic system. Two strategies have been developed for electron spin polarizing, which resort to heavy atom effect and magnetic induction respectively. Both theoretical and experimental studies show that controlling spin state of OH radicals in photocatalytic reaction can not only decrease OER over-potential (even to 0 eV) of water splitting, but improve stability and charge lifetime of photocatalysts. A convenient strategy have been developed for aligning spin state of OH by utilizing chiral molecules to spin filter photo-electrons. By chiral-induced spin filtering, electron polarization can approach to 74%, which is significantly larger than some traditional transition metal devices. Those achievements demonstrate bright future of spintronics in enhancing photocatalytic HER, nevertheless, there is little work systematically reviewing and analysis this topic. This review focuses on recent achievements of spintronics in photocatalytic HER study, and systematically summarizes the related mechanisms and important strategies proposed. Besides, the challenges and developing trends of spintronics enhanced photo-catalytic HER research are discussed, expecting to comprehend and explore such interdisciplinary research in photocatalytic HER. [ABSTRACT FROM AUTHOR]

Spin polarization at benzene/Ni organic/ferromagnetic interface is investigated by applying different substituting side groups. Based on first-principle calculations, it is demonstrated that the spin polarization of the states may be tuned in magnitude and sign by the side groups, which depends on the type of side groups as well as their position in the aromatic ring. Especially, a spatial spin polarization modulation is realized at the surface with the utilization of electron donating group NH 2 or electron accepting group NO 2. The analysis of projected density of states onto the p z orbital of carbon atoms indicates that the side group reduces the structural symmetry of the molecule and changes the p z orbital of carbon atom at different position, which further modifies the p z - d orbital hybridization as well as the spin transfer between the molecule and the ferromagnet. This work indicates a feasible way to modulate the spatial spin polarization at organic spinterface by side groups, which deserves to be measured by spin-polarized scanning tunneling microscopy. [ABSTRACT FROM AUTHOR]

First-principles calculation are presented to study the influences of external electric fields on the spin polarization properties of benzene/Cu(100) system which do not contain any magnetic atom. Our simulations show that an obvious spontaneous spin polarization oscillation occurred in the benzene molecule when the electric fields are applied. The density of states (DOS), spin density distributions, charge transfer properties are also obtained. It is found that the p-d orbital coupling between the benzene molecule and the electrode leads to spin non-degeneration of the DOS near the fermi energy, so the transferred charges from the Cu atoms to the molecule will fill these spin non-degenerate coupled orbitals, and then the benzene molecule becomes spin polarized. The strength of the p-d orbital coupling as well as the transferred charges oscillated with the external electric fields, which induce spin polarization oscillation. The results are favorable for the understanding of spin polarization properties in organic/nonmagnetic metal structures. [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]

By first-principles calculations, we investigated the electronic structures and magnetic properties of several tetravalent transition-metal monolayers with normal honeycomb, triangular-dodecagonal, and square-octagonal structures by considering the effects of spin-orbit coupling and electronic strong correlation of d orbitals. For both standard and corrected approaches, spin-polarized Dirac points contributed by d states appear in the monolayers with hexagonal lattice (honeycomb and 3–12 lattices), but for 4–8 lattices, Dirac points disappear, demonstrating that specific symmetries are required for forming Dirac cones. By adding the on-site Coulomb repulsion, the electronic correlation of d orbital is enhanced and thus the electronic localization increases, aggravating the spin splitting. For Hf3-12, the coexistence of massless Dirac fermions and massive heavy fermions is found. Moreover, the spin-orbit coupling destroys the degeneracy of two bands at K points, and the largest gap opening of 214 meV appears in Hf4-8 due to both Coulomb repulsion and spin-orbit coupling. Our results demonstrate that the spin splitting and gap opening depend on the lattice symmetry, bond length, electronic strong correlation, and spin-orbit coupling. These predicted structures provide new choices in synthesizing two-dimensional transition-metal materials, which has the potential applications in spintronic devices, quantum computation, hydrogen storage, and catalytic chemistry. [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]

Oxygen vacancy induced ferromagnetic coupling in diluted magnetic oxide (DMO) semiconductors have been reported in several studies, but technologically more crucial spin-polarized current (SPC) is still under-developed in DMOs. Few studies have claimed that VRH mechanism can originate the SPC, but, how VRH mechanism associated with percolation path, is not clearly understood. We used Point-contact Andreev reflection (PCAR) technique to probe the SPC in Co-doped ZnO (CZO) films. Since the high resistance samples cause broadening in conductance(G)-voltage(V) curves, which may result in an unreliable evaluation of spin polarization, we include two extra parameters, (i) effective temperature and (ii) spreading resistance, for the simulation to avoid the uncertainty in extracting spin polarization. The effective G-V curves and higher spin polarization can be obtained above a certain oxygen vacancy concentration. The number of completed and fragmentary percolation paths is proportional to the concentration of oxygen vacancies. For low oxygen vacancy samples, the Pb-tip has a higher probability of covering fragmentary percolation paths than the complete ones, due to its small contact size. The completed paths may remain independent of one another and get polarized in different directions, resulting in lower spin-polarization value. High oxygen vacancy samples provide a high density of completed path, most of them link to one another by crossing over, and gives rise to high spin-polarization value. [ABSTRACT FROM AUTHOR]

Control of organic interfacial spin polarization is crucial in organic spintronics. Based on ab initio theory, here we proposed a spin selection at organic interface via anchoring group by adsorbing an organic molecule onto Ni(111) surface. The results demonstrate that either a positive or negative interfacial spin polarization may be obtained by choosing different anchoring groups. The orbital analysis via the projected density of states shows that the interfacial spin polarization is sensitive to the hybridization of the outer orbital of the anchoring atom as well as its energy relative to the d orbital of the ferromagnetic atom. The work indicates a feasible way to realize spin selection at the organic spinterface by anchoring group. [ABSTRACT FROM AUTHOR]

First-principles spin-polarized calculations are performed to design lithium storage materials using the active edges of zigzag silicene nanoribbon (ZSiNR). We predict that edge-adsorption of Li adatoms on zigzag silicene nanoribbon is preferred in energy to form new type lithium storage materials. Significant charge transfer from Li adatoms to Si atoms at the edges of ZSiNR is found, indicating the main ionic interactions. It is found that the band structures of ZSiNR with Li adsorptions are sensitive with the variation of sites of adatoms at the two edges. Ferro-magnetic to antiferro-magnetic change is found in ZSiNR with symmetrical adsorption of Li adatoms at its two edges. Other unsymmetrical Li adsorptions at the edges of ZSiNR prefer to stay in ferro-magnetic state as that in narrow pristine ZSiNR. [ABSTRACT FROM AUTHOR]

Magnetic tunnel junctions (MTJs) both with efficient spin-filtering effect and large tunneling magnetoresistance (TMR) ratio are extremely attractive and highly desirable in the field of spintronics. Inspired by recent successful preparation of a stable two-dimensional (2D) layered ferromagnet 1T-CrSe 2 on a 2H-WSe 2 substrate via chemical vapor deposition (CVD) synthesis, herein, employing first-principles calculations, we investigate the spin-dependent transport properties of van der Waals (vdW) MTJs built with a monolayer 2H-WSe 2 tunnel barrier and a 1T-CrSe 2 single-electrode or a 1T-MoSe 2 /1T-CrSe 2 dual-electrode. Compared to low TMR (67.3%) in single-electrode MTJ, dual-electrode MTJ exhibits excellent spin-filtering effect (with 99.96% spin polarization) and a giant TMR ratio (up to 2.29 × 105%), which mainly originates from the half-metallicity of CrSe 2 induced by charge transfer at MoSe 2 /CrSe 2 interface. Relatively high TMR values (over 1 × 103%) are always maintained at small bias voltages (| V b | ≤ 0.35 V). Our work have for the first time theoretically verified feasibility of realizing the transition of 2D CrSe 2 from metallicity to half-metallicity in the vdW MTJ and yielding excellent spin-filtering and giant magnetoresistance via electrode interface engineering, thereby providing important theoretical guidance for the experimental design of high-performance vdW MTJs in spintronic devices. [Display omitted] • A huge magnetoresistance up to 2 × 105% is realized in dual-electrode MTJ based on 1 T-CrSe 2 monolayer. • Electrode interface engineering renders half-metallicity of CrSe 2 and nearly 100% spin polarization of dual-electrode MTJ. • High magnetoresistance (over 103%) is maintained at small bias voltage (| V b | ≤ 0.35 V). [ABSTRACT FROM AUTHOR]

[Display omitted] • Effects of the vacancy is mainly depended upon edge configuration of the ribbon. • Half-metallicity can be realized in zigzag BPNR with phosphorus vacancy. • Charge injection and transverse electric field can raise spin-polarization with B-vacancy. • Perfect bipolar spin filtering effect observed with a B-vacancy near rich-P edge. Edge states and vacancy-induced defect states simultaneously occur near Fermi level of boron-phosphide nanoribbon (BPNR) when there is a vacancy in it, which is a compromise of two important influencing factors for electronic property modulation. Based on density functional theory, the effects of mono-vacancy on electronic structure of zigzag/armchair BPNRs have been investigated. Calculation results indicate that effects of the vacancy on electronic property of the system is mainly depended on edge configuration of the ribbon. Half-metallicity can be realized in zigzag BPNR with phosphorus vacancy. Furthermore, it is found that charge injection and transverse electric field can raise spin-polarization of zigzag BPNR with boron vacancy near rich-B edge. Most interestingly, it exhibits perfect bipolar spin filtering effect for the case of zigzag BPNR with a boron vacancy near rich-P edge. [ABSTRACT FROM AUTHOR]

Spin polarized first principles total energy calculations have been applied to study the stability and magnetic properties of the MnGa(001) surface and the formation of a topmost MnN layer with the deposit of nitrogen. Before nitrogen adsorption, surface formation energies show a stable gallium terminated ferromagnetic surface. After incorporation of nitrogen atoms, the antiferromagnetic manganese terminated surface becomes stable due to the formation of a MnN layer (Mn-N bonding at the surface). Spin density distribution shows a ferromagnetic/antiferromagnetic arrangement in the first surface layers. This thermodynamically stable structure may be exploited to growth MnGa/MnN magnetic heterostructures as well as to look for exchange biased systems. [ABSTRACT FROM AUTHOR]

First principles calculations are adopted to study the spin polarization properties of thiophene molecule which adsorbed at the Co, Fe, and Ni electrode surfaces. The density of states, spin-polarized density distributions as well as the differential charge density distributions are obtained. It is found that the p orbital of the thiophene molecule will interact with the d orbital of the ferromagnetic electrodes, which will generate new spin coupling states and lead to obvious spin polarization in the thiophene molecule. Different electrodes induce different spin polarization properties, and in which the Fe electrode will bring the biggest spin polarization of the thiophene molecule. People can selectively and efficiently inject spin polarized electrons into molecules by choosing suitable ferromagnetic electrodes in organic spintronic devices. [ABSTRACT FROM AUTHOR]

Possible adsorption configurations of H and SiH x (x = 1 − 4) on clean and H-covered Si(100) surfaces are determined by using spin-polarized DFT calculations. The results show that, on the clean surface, the gas-phase hydrogen atom and SiH 3 radicals effectively adsorb on the top sites, while SiH and SiH 2 prefer the bridge sites of the first layer. Another possibility for SiH is to reside on the hollow sites with a triple-bond configuration. For a partially H-coverd Si(100) surface, the mechanism is similar but with higher adsorption energies in most cases. This suggests that the surface species become more stable in the presence of surface hydrogens. The minimum energy paths for the adsorption/migration and reactions of H/SiH x species on the surfaces are explored using the climbing image-nudged elastic band method. The competitive surface processes for Si thin-film formation from SiH x precursors are also predicted. The study reveals that the migration of hydrogen adatom is unimportant with respect to leaving open surface sites because of its high barriers (>29.0 kcal/mol). Alternatively, the abstraction of hydrogen adatoms by H/SiH x radicals is more favorable. Moreover, the removal of hydrogen atoms from adsorbed SiH x , an essential step for forming Si layers, is dominated by abstraction rather than the decomposition processes. [ABSTRACT FROM AUTHOR]

Diverse electronic structures can be achieved by N-substitution in stable two-dimensional dumbbell carbonitrides. [Display omitted] • A new structure, the DB-C structure, is proposed based on the dumbbell structure predicted in group-IV (Si, Ge, and Pb) monolayer. • Different kinds of DB-C x N y are formed by substituted doping of the C atoms at the bulged site with different amount of N atoms in the DB-C structure. • DB-C 4 N-1 and DB-C 4 N-2 hold the Dirac electronic state with a gap-opening under the influence of spin–orbit coupling. • The DB-C 7 N 3 monolayer is a bipolar magnetic semiconductor. The two-dimensional carbonitrides (C x N y) are attractive materials and their diversified properties play an important role in various fields. In this paper, a dumbbell C x N y is proposed. As graphene is a zero band-gap semiconductor with Dirac cone, while the DB-C monolayer formed by adding C atoms to graphene is an indirect-gap semiconductor with a band-gap of 1.69 eV. The various DB-C x N y are formed by substituted doping of the C atoms at the bulged site with different amount of N atoms. There are four bulged C in a unit cell of DB-C. DB-C 9 N has a metallic behavior, evolved by n-type doping. DB-C 4 N-1 and DB-C 4 N-2 hold the Dirac electronic state with a gap-opening under the influence of spin–orbit coupling, while DB-C 4 N-3 is an indirect-gap semiconductor. Of all DB-C x N y , only DB-C 7 N 2 and DB-C 7 N 3 are magnetic, but DB-C 7 N 2 has a metallic behavior and DB-C 7 N 3 is a bipolar magnetic semiconductor with controllable spin polarization. DB-C 6 N 4 is a nonmagnetic semiconductor with a direct band-gap of 0.80 eV. The stability of all DB-C x N y monolayers is verified by the phonon spectrum. Due to the unique geometric structure, tunable electronic properties, and high specific surface area, DB-C x N y monolayers may be well applied in photocatalysis, electrocatalysis, spintronic and energy storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe and Ni multilayer epitaxy is realized on oxygen-passivated Fe(0 0 1). • Oxygen floats on the surface and affects the magnetic response of the system. • The spin polarization of the photoemission signal is quenched upon Ni growth. • A single Fe layer abruptly restores the polarization signal. • According to simulations, the spectral polarization follows surface magnetization. We investigated the magnetic behaviour of an Fe overlayer on a Ni buffer layer (Fe/Ni multilayer system) grown on top of the Fe- p (1 × 1)O surface, with a particular focus on the modifications observed in the spin-resolved electronic structure and the role of oxygen, introduced in the system in a well-defined amount at the substrate preparation stage. The structural properties are investigated by means of low energy electron diffraction, that confirms the formation of an epitaxial system featuring a metastable surface lattice. Spin-resolved photoemission spectroscopy testifies a strong decrease of the spectral spin polarization for increasing thickness of the Ni buffer layer, reaching a minimum from a nominal thickness of 6 Ni atomic layers. Surprisingly, the growth of a single Fe overlayer is sufficient to restore most of the original polarization signal, thus creating an ultrathin bcc Fe film seemingly decoupled from the substrate. Ab initio calculations track the modifications of the magnetic moments of the surface layers that quench upon Ni deposition and restore with additional Fe growth. Spin-resolved inverse photoemission highlights a notable reduction of the density of majority states just above the Fermi level, possibly influencing the magnetic response of the system. [ABSTRACT FROM AUTHOR]

Because of this lattice mismatch, the tetragonal FM Mn 3 Ge grown along c -axis on STO will definitely be stretched at the interface. The thickness dependent double-phase Mn 3 Ge films with large magnetic anisotropy and robust anomalous Hall effect were obtained. [Display omitted] • The high quality perpendicularly magnetized Mn 3 Ge films were grown by magnetron sputtering. • XRD shows that hexagonal antiferromagnetic Mn 3 Ge is mixed with tetragonal ferromagnetic Mn 3 Ge. • The thickness dependent double-phase Mn 3 Ge films with large magnetic anisotropy and robust anomalous Hall effect were obtained. Mn 3 Ge, a typical member of the Heusler family, has a high spin polarization and large spin Hall angle, making it a potential material for spintronic devices. Regarded as a topological Weyl semi-metal, Mn 3 Ge could be applied in topological spintronics owing to its special Fermi-arc-type surface states and various spin transport properties. In this study, we grew high-quality perpendicularly magnetized Mn 3 Gefilms through magnetron sputtering. X-ray diffraction (XRD) showed that hexagonal antiferromagnetic Mn 3 Ge was mixed with tetragonal ferromagnetic Mn 3 Ge. Thickness-dependent double-phase Mn 3 Ge films with large magnetic anisotropy and robust anomalous Hall effect (AHE) were obtained. The triangular spin structure of hexagonal Mn 3 Ge enhances the AHE; however, it shrinks the coercivity of the tetragonal ferromagnetic property. This manipulation of coexisting multi-phases comes from the strain of the substrate during growth, achieved by controlling the film thickness. Structural, magnetic, and transport measurements demonstrated stress modulation of the defect pinning, magnetic anisotropy, and spin transport properties. The coexistence of antiferromagnetic and ferromagnetic Mn 3 Ge provides the possibility of a new generation of Mn 3 X-based devices for applications in spin-torque memories. [ABSTRACT FROM AUTHOR]

Electronic and magnetic properties of silicene functionalized by H, C, and F atoms at different coverages are studied based on density functional theory. For H and F adatoms, the most stable adsorption sites are top sites. The situation is different for C adatom, and its most preferable adsorption site is valley site. Among the three kinds of adatoms, the magnetism can always be induced by H adsorption, while spin polarization is triggered only in silicene with low C concentration. The F adsorption mainly changes sites of Fermi level. The various band structures of metal, spin gapless semiconductor, and semiconductor can be obtained. [ABSTRACT FROM AUTHOR]

Electronic structure of ultrathin Ag films on Si(111) is investigated with spin- and angle-resolved photoemission spectroscopy using unpolarized light. Photoelectrons leaving d states of Ag reveal spin polarization with the polarization vector parallel to the sample surface. The effect is observed for the Ag films which have bulk-like crystallographic structure with coverages down to 1 monolayer, for Ag wetting layer on Si(111)-(7 × 7) and Si(111)- ( 3 × 3 ) Ag surface. It is found that the polarization magnitude increases with Ag thickness. The observed changes have been attributed to the changes in the Ag film morphology. [ABSTRACT FROM AUTHOR]

Interface characteristics of Co 2 MnSi/Ag/Co 2 MnSi trilayer have been investigated by means of first-principles. The most likely interface is formed by connecting MnSi-termination to the bridge site between two Ag atoms. As annealed at high temperature, the formation of interface DO 3 disorder is most energetically favorable. The spin polarization is reduced by both the interface itself and interface disorder due to the interface state occurs in the minority-spin gap. As a result, the magneto-resistance ratio has a sharp drop based on the estimation of a simplified modeling. [ABSTRACT FROM AUTHOR]

Understanding the interfacial behavior at FM-OSC-FM hybrid structures for both the bottom contact (Alq 3 adsorption on Co, Co/Alq 3 ) and the top contact (Co atop Alq 3 , Alq 3 /Co) is crucial for efficient spin filtering with transport of spin-polarized charge carriers through these interfaces. X-ray photoelectron spectroscopy (XPS) spectra indicate a symmetry of charge transfer from Co to Alq 3 and the corresponding orbital hybridization to a certain extent at both contacts. The alignment of energy levels at both Alq 3 /Co and Co/Alq 3 heterostructures is depicted with ultraviolet photoelectron spectroscopy (UPS). Through magnetic images acquired with a X-ray photoemission electron microscope (XPEEM), the strong hybridization of the top contact presents no micromagnetic domain but still shows magnetic coupling, to some extent, to the bottom contact in the Co–Alq 3 –Co trilayer structure. Measurements of X-ray magnetic circular dichroism (XMCD) demonstrate the induced spin-polarization of non-magnetic Alq 3 at both contacts, proving Alq 3 a unique and promising organic material for spin filtering in OSV. [ABSTRACT FROM AUTHOR]

[Display omitted] • A highly efficient molecular SAC has been found whose nitrogen reduction efficiency is comparable to other known SACs. • CrCp and MnBz have extremely low limiting potentials of −0.29 V and −0.37 V, respectively. • In-depth research on the reaction mechanism found that the local magnetic moment plays a key role in the activation of nitrogen. • The descriptor of ΔE(*N 2 H) was discovered, and the mechanism was further investigated. The coordination environment of metal atoms in single-atom catalysts (SACs) has a greater impact on the catalytic performance of electrocatalysts. However, the influence mechanism of interacting ligands on the electrocatalytic nitrogen reduction reaction (NRR) process is still insufficient. Herein, by means of large-scale density functional theory (DFT) computations, the effect of organic ligands on the NRR process is investigated in-depth using half organometallic sandwich molecular SACs, i.e. TMBzs and TMCps (Bz = benzene, Cp = cyclopentadienyl, and TM = transition metal). The results revealed that the NRR performance of all the systems is highly dependent on the choice of d - π interaction within the TM-Ligand complexes. Compared with TMBzs, the TMCps exhibit outstanding NRR activity and significantly suppress HER. Among 16 candidates, CrCp and MnBz are the most promising candidates with an ultra-low limiting potential of −0.29 V and −0.37 V via consecutive mechanism, respectively. Moreover, the systems with higher spin polarizations have better NRR activity. The work provides new insight into the NRR to molecular SACs with different organic ligands. [ABSTRACT FROM AUTHOR]

The structural and electronic properties of the bulk and low-index (0 0 1) and (1 1 0) surfaces of the MnCo 2 O 4 spinel have been studied from the spin-polarized GGA + U calculations. Results show that Mn prefers to occupy the octahedral sites and exhibits as high-spin Mn 3+ while half Co takes the tetrahedral sites as high-spin Co 2+ and the other half takes the octahedral sites as nonmagnetic Co 3+ . The electronic structure of the MnCo 2 O 4 bulk is insulating with very small gap of about 0.03 eV. The surface atomic relaxations and surface energies are calculated with different terminations and stable MnCo 2 O 4 (0 0 1) and (1 1 0) surface models are obtained. The electronic structures of the Mn and the tetrahedral site Co atoms at the MnCo 2 O 4 (0 0 1) and (1 1 0) surfaces resemble their bulk characters. However, due to the lowered Co–O coordination, the electronic structure of the octahedral Co atoms changes substantially from the bulk state t 3 2g (↑)t 3 2g (↓) into the surface state t 3 2g (↑)e 1 g (↓) t 2 2g (↓) at the MnCo 2 O 4 (0 0 1) surface (5-coordinated Co) and t 3 2g (↓)e 2 g (↓)t 1 2g (↓)e 1 g (↓) at the MnCo 2 O 4 (1 1 0) surface (4-coordinated Co). [ABSTRACT FROM AUTHOR]

Spin-polarized density functional theory calculations were carried out to investigate the adsorption of Hg n ( n = 1–3) on the perfect, step and vacancy-defective Pd(1 1 1) surfaces as well as the Pd/γ-Al 2 O 3 (1 1 0) surface. It is found that Hg atoms prefer to adsorb on the hollow sites on Pd(1 1 1) surfaces. The adsorption of Hg on the step and vacancy-defective Pd(1 1 1) surfaces is stronger than on the perfect Pd(1 1 1) surface, which indicates that the existence of vacancy and step defects can enhance the mercury adsorption activity of Pd adsorbents. As indicated by the calculated adsorption energies, the mercury adsorption on γ-Al 2 O 3 is weak. The γ-Al 2 O 3 supported single Pd atom shows as good Hg adsorption activity as the perfect Pd(1 1 1) surface at low Hg coverage, while more coordination unsaturated active Pd atoms is needed to achieve high Hg adsorption capacity. In addition, it was also found that the Hg adsorption on Pd/γ-Al 2 O 3 weakens the binding of Pd to the γ-Al 2 O 3 surface. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) layered electrides are a new class of 2D materials with interstitial anionic electrons. We report a first-principles study of the Ca 2 N and Y 2 C bilayers, well-known 2D electrides. When one of the two layers is translated, rotated horizontally (∼ 21. 8 °), or compressed vertically, the electronic and magnetic properties are changed. When pressure is applied perpendicular to the layer plane, the electrons in the interlayer region are not uniformly distributed and localized; this is more pronounced in Y 2 C than Ca 2 N. For lateral sliding in the bilayer, the energy barrier of Ca 2 N is lower than that of Y 2 C. Sliding changes or breaks the symmetry, changing the energy band structure of the material, and a change in the local spin polarization occurs in the Y 2 C bilayer. Finally, the investigation of twisted electride bilayers indicates the generation of a Moiré pattern as seen in the scanning tunneling microscopy image of Y 2 C. Besides, the spin density appears on the surface as well as in the interlayer region. Our study opens the possibility of using electride layers in straintronics and twistronics. [Display omitted] • On compressing the Ca 2 N or Y 2 C bilayer, the electrons collected between the layers become more localized. • The Fermi velocity changes because of the change in the electronic structure due to compression. • Lateral sliding results in a change in the local spin polarization of the Y 2 C bilayer. • By twisting the Y 2 C bilayer, the spin density is generated not only in the interlayer region but also above the bilayer surface. • Our study opens up the possibility of using electride layers in straintronics and twistronics. [ABSTRACT FROM AUTHOR]

The adsorption properties of CO on the nondefective and defective (with an oxygen vacancy) B-layer Fe 3 O 4 (0 0 1) surfaces (an octahedral environment of iron ions) at different coverages are studied using the spin-polarized density functional theory with the inclusion of on-site Coulomb interaction by introducing Hubbard U parameter (DFT + U) method. It is found that the CO adsorption energy in general increases with the CO coverage. Both types of B-layer Fe 3 O 4 (0 0 1) surfaces have the excellent ability for CO oxidation. Comparatively, the defective B-layer Fe 3 O 4 (0 0 1) surface has a much stronger CO adsorption ability and a lower CO oxidation ability than the nondefective B-layer Fe 3 O 4 (0 0 1) surface. The density of state reveals the bonding mechanism of CO on the two surfaces. The effects of the ambient conditions on the CO adsorption processes are analyzed. [ABSTRACT FROM AUTHOR]

We report a theoretical study on spin-polarized lateral displacement for the electron across a magnetic nanostructure with a zero average magnetic field, which can be experimentally realized by depositing a ferromagnetic stripe with a plumb magnetization on the top of a semiconductor heterostructure. It is shown that, the lateral displacement depends strongly on the electron spins due to the Zeeman coupling and the intrinsic symmetry, though the average magnetic field is vanishing in the nanostructure. It is also shown that the spin-polarized lateral displacement is related closely to the structural parameters. Therefore, such a novel magnetic nanostructure may be used as a spin spatial splitter for spintronics applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Spin-polarized effects were included into the orbital-dependent 3D WKB tunneling model. [•] Orbital contributions of the tunneling current were analyzed above the Fe(110) surface. [•] The STM contrast inversion is sensitive to the spin-polarization and tip magnetization. [•] Qualitative agreement of the corrugation character found with the Tersoff–Hamann model. [•] Simulated constant-current STM images demonstrate the contrast inversion. [Copyright &y& Elsevier]

Highlights: [•] Ta/AlN/Ni81Fe19/AlN/Ta films were prepared by magnetron sputtering. The electronic transport properties were studied. [•] Chemical status change at the NiFe/AlN interface was quantified by X-ray photoelectron spectroscopy. [•] The average grain size as well as the crystallinity was determined from X-ray diffraction studies. [•] The relative contributions of surface and grain boundary scattering to the electrons transport were analyzed. [ABSTRACT FROM AUTHOR]

Highlights: [•] We observe significant room temperature ferromagnetism in indium oxynitride, Cr substituted indium oxynitride, and high quality InN films. [•] The conducting films show a substantial degree of spin polarization at low temperature. [•] The presence of magnetism in all samples suggests that intrinsic effects may be responsible for the spin ordering. [ABSTRACT FROM AUTHOR]

Abstract: We theoretically investigate the electron transport properties in a non-magnetic heterostructure with both Dresselhaus and Rashba spin–orbit interactions. The detailed-numerical results show that (1) the large spin polarization can be achieved due to Dresselhaus and Rashba spin–orbit couplings induced splitting of the resonant level, although the magnetic field is zero in such a structure, (2) the Rashba spin–orbit coupling plays a greater role on the spin polarization than the Dresselhaus spin–orbit interaction does, and (3) the transmission probability and the spin polarization both periodically change with the increase of the well width. [Copyright &y& Elsevier]

The schemes of density of states n(E) as a function of energy for (a) half-metal semiconductors (HMS), (b) half-semiconductors (HSC), and (c) bipolar magnetic semiconductors (BMS). Black and red represent the spin-up and spin-down states, respectively. (d) Top view of pristine VI 3 and (e) top view of 3d transition metal (TM) doped VI 3. Red, grey, and orange balls represent V, I, and TM atoms, respectively. The light blue box outlines the primitive cell. Our calculations indicate that pristine VI 3 possesses HMS characteristics. VI 3 electronic and magnetic properties can be tuned effectively. We discovered HMS, HSC, and BMS properties by 3d TM interstitial doping VI 3. These materials with enhanced magnetic moments and diverse electronic structures hold great potential for next-generation semiconductor spintronic applications. [Display omitted] • The electronic and magnetic properties of 3d transition metal (TM) doped VI 3 were theoretically studied. • Desirable semiconductor spintronic materials with diverse electronic properties were discovered. • The magnetic moment of VI 3 was enhanced from 4 μ B to 11 μ B. • Extra 3d electrons from 3d TM doping greatly affected the electronic behavior and magnetism. Two-dimensional (2D) materials with robust magnetism have drawn immense attention for their promising applications in spintronics. Recently, intrinsic ferromagnetic vanadium triiodide (VI 3) has been synthesized experimentally. To enhance its spintronic property, we modified VI 3 by interstitial doping with 3d transition metals (TM) and used first-principles calculations to investigate the geometric structure, formation energy, electronic property, and magnetism of pristine VI 3 and 3d TM-doped VI 3 monolayer. Among eight transition metal (Sc-, Ti-, V-, Cr-, Mn-, Fe-, Co-, and Ni-) doped VI 3 materials, four of them (Ti-, V-, Mn-, and Ni-doped VI 3) show robust magnetism with full spin polarization near the Fermi energy. Our research demonstrates that Ti-doped VI 3 results in half-metallic semiconductor properties (HMS), while V-doped VI 3 and Ni-doped VI 3 result in half-semiconductor properties (HSC). Surprisingly, Mn-doped VI 3 exhibits an unusual bipolar magnetic semiconductor property (BMS). This unique combination of strong ferromagnetism and 100% spin polarization with a half-metallic, half-semiconductor, or bipolar semiconductor property renders 3d TM-doped VI 3 as potential candidates for next generation semiconductor spintronic applications. These spin-polarized materials will be extremely useful for spin-current generation and other spintronic applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The spin states of TMN 4 -G (TM = Mn, Fe and Co) transfer between low- and high-spin states at critical strains. • Spin polarization turn up in nonmagnetic ScN 4 - and NiN 4 -G, and turn off in magnetic CuN 4 -G under certain strains. • The origin of the spin-state transitions is related with the TM valance electrons and charge transferred. Spin-tunable materials are very appealing for applications in multifunctional spintronics devices because of their ability to switch between different spin states with external stimuli such as strain, light or electric-field, etc. As a promising material for spintronics, transition-metal-nitrogen-carbon (TM-N-C) materials have achieved considerable attentions. Based on density functional calculations, we systematically investigate the magnetic properties of four-nitrogen coordinated transition-metal embedded graphene (TMN 4 -G, TM = all 3 d -elements). The embedded configurations of TMN 4 -G show rich tunable spin states by external strains, exhibiting two kinds of spin-state transitions: 1) Spin crossover between low- to high-spin states (TMN 4 -G, TM = Mn, Fe and Co); 2) Spin polarization turned up or turned off in nonmagnetic systems (ScN 4 -G and NiN 4 -G) or in magnetic CuN 4 -G, respectively. The spin-state transitions occur abruptly for systems with magnetic TM elements, while continuously for those with nonmagnetic elements. The origin of the spin-state transitions is explored and found related with the TM valance electrons and charge transferred. Our findings could open an avenue for the efficient tuning of spin and magnetism in graphene based TMN 4 structures for application in spintronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Induce half metallicity in bilayer VS 2 when interfaced with Janus MoSSe Monolayer. • half metallicity is mainly driven by inbuilt polarization of MoSSe. • Induction of half metallicity is also facilitated by hybridization of d z2 orbitals. • Required electric field to induce half metallicity is reduced by charge transfer. Half metallic 2D materials with 100% spin polarization at the fermi level can be applied to spintronics to enhance the device efficiency. We identified that the Janus MoSSe monolayer can induce halfmetallicity in the VS 2 bilayer whose ground state magnetic order remains in an antiferromagnetic configuration. We established that half-metallicity in the bilayer VS 2 is caused by the induced electric field originating from the out-of-plane electrical polarization of the Janus MoSSe layer, charge transfer between MoSSe and VS 2 layers and inter layer hybridization in Mo and V atom d z2 orbitals. We also established that the Interlayer charge transfer between MoSSe and VS 2 layers has largely reduced the required electric field to induce the half metallicity by shifting the electronic bands closer to the fermi level. Otherwise, inbuilt electrical polarization generated by Janus MoSSe layer becomes insufficient. This highlight that the external electric field which is required to induce half metallicity can be reduced by manipulating the charge transfer. These novel findings can be adopted to induce half metallic characteristics to many magnetic materials used in spintronic devices, and in the foreseeable future. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stable nitrogene monolayer has an indirect band gap of 6.023 eV. • AA-, AA′-, and AB-stacked bilayers show good stability with reduced energy gap. • Magnetic semiconductor magnetic nature is induced by C-doping. • B-doping leads to magnetism-free materials, with considerable band gap reduction. • Codoping can be considered of the combined effects of separated C- and B- doping. The (N) nitrogen monolayer (nitrogene) has been predicted to be stable in the buckled hexagonal structure. However the non-magnetic nature and large band-gap may restrict its practical applications. In this paper, the electronic and magnetic properties of the nitrogene monolayer and bilayer doped with carbon (C) and boron (B) are investigated using first-principles calculations. Nitrogene monolayer is a non-magnetic two-dimensional (2D) material with an indirect band-gap of 4.185(6.023) eV determined by the PBE(HSE06) functional. Nitrogene bilayers with different stacking shaps are examined. Results reveal dynamical stability of the AA-, AA′-, and AB-stacked bilayers. Such atomic arrangements depict an energy gap reduction as compared to that of the monolayer. C doping causes strong spin polarization at the vicinities of the Fermi level, giving place to magnetic semiconductor nature. The magnetic properties are produced mainly by the C dopants (0.7 μ B ), and also proximity induced small contributions on the N atoms (0.07 μ B ). In contrast, B doping produces non-magnetic materials with band-gap reduction (∼ 12% and 20.5%) for all considered systems. When the co-doping is treated, the effect on the electronic and magnetic properties can be considered as the combined effects of the separated C doping and B doping. Results presented herein may propose an efficient method to functionalize the nitrogene monolayer and bilayer for practical applications in optoelectronic and spintronic nano devices. [ABSTRACT FROM AUTHOR]

Abstract: We have applied conventional Time Differential Perturbed Angular Correlation (TDPAC) method to observe the anisotropy oscillations in the 3γ annihilation decay of polarized Positronium in a weak magnetic field. The effect, as predicted theoretically and experimentally demonstrated by Barishevsky et al. [V.G. Barishevsky, O.N. Metelitsa, V.V. Tikhomirov, Oscillations of the positronium decay γ-quantum angular distribution in a magnetic field, J. Phys. B: At. Mol. Opt. Phys.22 (1989) 2835], is induced by the coherent admixture of the m =0 states of ortho-Positronium (o-Ps) and para-Positronium (p-Ps) in interaction with the magnetic field. The following experimental characteristics are to be considered: [(i)] the oscillation frequency corresponds to the difference in energy of the Ps atom levels in magnetic field and is proportional with H 2; [(ii)] in a fixed geometry the modulation depth (oscillations amplitude) depends on the mean positron polarization; [(iii)] privileged angles of the polarization vector, magnetic field and detectors are required for optimizing the observed oscillations amplitude. The normalized difference spectrum function (R(t)) obtained from time spectra measured in vacuum and in different gaseous atmospheres (Ar, H2, N2) have the oscillations amplitude constant and we conclude that the Ps atoms are not fully thermalized over a time interval of about 400ns. The R(t) functions obtained for o-Ps annihilation decays, in dry air or Ar–O mixture, have the oscillations amplitude time dependent due, probably, to the paramagnetism of the Oxygen molecules. [Copyright &y& Elsevier]

Abstract: We present a theoretical study on spin-dependent transport of electrons in any anti-parallel double -magnetic-barrier nanostructure, which can be experimentally realized by depositing a ferromagnetic stripe on the surface of a semiconductor heterostructure. A general fomula of tranmission probability for electrons tunneling through this kind of nanostructures, is obtained. It is shown that large spin-polarized current can be achieved in such a device. It also is shown that the degree of electron-spin polarization is strongly dependent upon magnetic-strength difference of two -barriers. These interesting properties may provide an alternative scheme to spin-polarize electrons into semiconductors, and this device may be used as a tunable spin-filter. [Copyright &y& Elsevier]

• Spin-polarized DFT has been employed to reveal the impact of various adsorbed molecules on the structural, electronic and magnetic properties of MoSi 2 N 4 (MSN) monolayer. • The effect of environmental and industry-relevant gas molecules was studied. • The interaction between the different molecules with the MSN is a physisorption type. • Our theoretical studies indicate that MSN-based sensor has a high potential for O 2 , NO, NO 2 and SO 2 detection. The adsorption of various environmental gas molecules, including H 2 , N 2 , CO, CO 2 , O 2 , NO, NO 2 , SO 2 H 2 O, H 2 S, NH 3 and CH 4 , on the surface of the recently synthesized two dimensional MoSi 2 N 4 (MSN) monolayer has been investigated by means of spin-polarized first-principles calculations. The most stable adsorption configuration, adsorption energy, and charge transfer have been computed. Due to the weak interaction between molecules studied with the MSN monolayer surface, the adsorption energy is small and does not yield any significant distortion of the MSN lattice, i.e., the interaction between the molecules and MSN monolayer surface is physisorption. We find that all molecules are physisorbed on the MSM surface with small charge transfer, acting as either charge acceptors or donors. The MSN monolayer is a semiconductor with an indirect band gap of 1.79 eV. Our theoretical estimations reveal that upon adsorption of H 2 , N 2 , CO, CO 2 , NO, H 2 O, H 2 S, NH 3 and CH 4 molecules, the semiconducting character of MSN monolayer is preserved and the band gap value is decreased to ~ 1.5 eV. However, the electronic properties of the MSN monolayer can be significantly altered by adsorption of O 2 , NO and SO 2 , and a spin polarization with magnetic moments of 2, 1, 2 μ B , respectively, can be introduced. Furthermore, we demonstrate that the band gap and the magnetic moment of adsorbed MSN monolayer can be significantly modulated by the concentration of NO and SO 2 molecules. As the concentration of NO 2 molecule increases, the magnetic moment increase from 1 μ B to 2 and 3 μ B . In the case of the SO 2 molecule with increasing of concentration, the band gap decreases from 1.2 eV to 1.1 and 0.9 eV. Obviously, our theoretical studies indicate that MSN monolayer-based sensor has a high application potential for O 2 , NO, NO 2 and SO 2 detection. [ABSTRACT FROM AUTHOR]

[Display omitted] • The valley polarization (VP) of the H-Tl 2 O/CrI 3 heterostructure is observed in both the conduction and the valence band. • A large valley spin splitting (VSS) of 0.57 (0.58) eV at the K (K') points are shown in the conduction band. • The VP and the VSS can be manipulated by adjusting the interlayer spacing and the in-plane biaxial strains. We report the two-dimensional H-Tl 2 O/CrI 3 van der Waals (vdW) heterostructure as a promising valleytronic material and investigate its valley polarization and valley spin splitting manipulation using first-principles calculations. The H-Tl2O/CrI 3 heterostructure displays valley polarization both in the conduction and valence band at two valleys. Particularly, valley polarization can attain 14.95 meV at the conduction band. In addition, a large valley spin splitting of 0.57 (0.58) eV at the K (K') point is shown in the conduction band. With the manipulation of the interlayer spacing and in-plane biaxial strain, the valley polarization and valley spin splitting of the H-Tl 2 O/CrI 3 heterostructure follow the short-range effects of interfacial orbital hybridization, thus a nearly linear relationship is shown. Our work provides not only application prospects of the H-Tl 2 O/CrI 3 heterostructure nanodevices but also theoretical effective support for research and development of valleytronics. [ABSTRACT FROM AUTHOR]