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Fe-based catalysts have a good prospect in oxygen reduction reaction (ORR) in fuel cells. However, the catalytic activity of Fe-based catalysts requires further improvement to satisfy the demand in industrial application and the working mechanism is still shrouded in ambiguity. Here, a ferromagnetic catalyst with nitrogen-doped carbon supported FeCoNi alloy was synthesized by impregnation-pyrolysis method. The micromorphology and structure of the catalyst was analyzed by XRD, SEM, TEM, XPS, BET and Raman spectroscopy. The trimetallic catalyst showed high ORR activity in 0.1 M KOH with a half-wave potential of 0.908 V and a limiting current density of 6.153 mA cm−2, which was superior to 20 % Pt/C. The synergistic effect of FeCoNi alloy regulated the spin polarization and the regulated spin state improved ORR performance by facilitating the adsorption of O 2 molecules and the conversion of the activated intermediates. [Display omitted] • FeCoNi@NC is derived from C 3 N 4 by impregnation-pyrolysis method. • FeCoNi@NC is highly active for oxygen reduction reaction. • The spin polarization is regulated by the synergistic effect of Fe, Co and Ni. [ABSTRACT FROM AUTHOR]

In this study, we investigate the effects of doping with ∼10 at% of Si, Al, Sn, and Bi on the atomic order, microstructure, and magnetic properties of CoMnSb samples prepared using the arc-melting method. X-ray diffraction, scanning electron microscopy, and magnetometry techniques were employed to derive the structural and magnetic parameters. The samples demonstrate a superstructure with an Fm -3 m space group. They exhibit a saturation moment of 3.71–4.71 μ B per formula unit at 5 K and a Curie temperature ranging from 474 to 507 K. Rietveld refinement performed on the XRD data revealed a possible occupation of magnetic atoms in the vacant 32 f (x ', x ', x ') sites and atomic swapping, both of which may affect the magnitudes of the magnetic moment and Curie temperature. The electrical measurement results show that the grain boundaries and voids govern the conductivity of the samples. The spin polarization of the Si-doped sample was determined based on the grain-boundary magnetoresistance effect, which showed that this sample has a high degree of atomic order, consistent with the low magnetic moment, Curie temperature, and lattice constant. [ABSTRACT FROM AUTHOR]

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]

• We dope paramagnetic iron ions (Fe2+) into colloidal metal halide perovskite nanocrystal (PNC). • Incorporating a magnetic dopant and applying an external magnetic field induce spin polarization. • The spin polarized photo-excited electrons enhance the photocatalytic CO 2 reduction efficiency. • Applying an external magnetic field with Fe-doped PNCs, we achieve a CO 2 reduction rate of 133.04 μmol g−1. • This shows a 1.68-fold increase in CO 2 reduction rate compared to magnetic field-free Fe-doped PNCs. Spin manipulation offers an effective strategy to enhance photocatalytic activity in metal halide perovskites by suppressing the recombination of photo-excited electrons. However, the scope of the magnetic dopant inducing spin polarization is still limited. Here, we introduce synergetic strategies to polarize the spin in photo-excited electrons and boost their photocatalytic activity for CO 2 reduction. We dope iron cation (Fe2+) into CsPbBr 3 perovskite nanocrystals (PNCs). Fe ions induce paramagnetism, fostering spin polarization within the Fe-doped CsPbBr 3 PNCs (Fe-CsPbBr 3 PNCs) under magnetic fields. The magnetic compositions in PNC tend to stabilize the spin polarized electrons within the PNC, mitigate the recombination of photo-excited electrons and enhance the redox reaction for photocatalytic CO 2 reduction. The synergistic effects of magnetic element doping and the application of magnetic fields resulted in a photocatalytic CO 2 reduction of 133.04 μmol g−1, which is 1.68-fold increase compared to the Fe-PNC without a magnetic field. This work provides a simple and environmentally friendly approach to CO 2 reduction based on PNCs. [ABSTRACT FROM AUTHOR]

Rhenium-based double perovskite oxides (DPOs) are a particularly fascinating class of materials because of high carrier spin polarization, large magnetic anisotropy energy (MAE), and complex electrical behavior along with high Curie temperature (T C). Herein, we discussed the impact of biaxial ([110]) strain ranging from − 5% to ＋ 5% along the a b -plane on the electronic and magnetic properties of CaCuFeReO 6 (CCFRO) DPO using a b - i n i t o calculations. The unstrained system exhibits a ferrimagnetic (FiM) spin ordering as an energetically stable magnetic ground state due to electron hopping between Fe + 3 /Re + 5 t 2 g and Cu + 2 e g orbitals along with a metallic electronic state. Moreover, [010] (b -axis) is the magnetic easy axis that produces the MAE of 5.36 meV, giving a giant MAE constant of 1.97 × 1 0 7 erg/cm 3. The evaluated partial spin-magnetic moment on the Cu1/Cu2/Fe/Re ion is 0.14/0.44/4.04/ − 0. 64 μ B , where " − " sign on the Re moment means that its spin is antiparallel to the other ions, verifying the FiM ordering in the system. Also, the e g , t 2 g / e g , and t 2 g orbital characteristics of Cu + 2 , Fe + 3 , and Re + 5 ions are visible in the spin-magnetization density iso-surfaces plots, respectively. Using the classical Heisenberg model, the computed T C for the unstrained structure is 576 K, which is quite close to the experimentally reported value of 567 K. In addition, it is shown that the FiM metallic behavior in the motif is robust against biaxial ([110]) strain within the considered range. It has also been revealed that T C increased to 5.73%/3.30% for the considered range of − 5% compressive/＋5% tensile strain due to improved structural distortions. [Display omitted] • A ferrimagnetic (FiM) state is found the energetically stable one. • [010] (b-axis) is the magnetic easy axis having MAE of 5.36 meV, giving a giant MAE constant of 1.97 × 107 erg/cm 3. • T C increased to 5.73%/3.30% for the considered range of −5% compressive/+5% tensile strain. [ABSTRACT FROM AUTHOR]

The spin-dependent conductance and spin polarization are investigated theoretically in a phosphorene superlattice in the presence of external magnetic field and Rashba interaction. It is demonstrate that, the spin-dependent conductance with and without spin-flip as well as spin polarization can be effectively controlled by changing the magnetic field strength and the number of the superlattice barriers. For small magnetic field strength, the conductance for with and without spin-flip shows an oscillating behavior as increasing the strength of the Rashba interaction, and by increasing the number of barriers, the oscillating behavior becomes prominent. Further, when the magnetic field is greater than a limit value, the spin conductance will be zero. The size of the spin-dependent transmission window in the phosphorene superlattice under external magnetic field decreases drastically. The magnitude, sign and behavior of the spin polarization can be tuned by the amount of the external magnetic field. [ABSTRACT FROM AUTHOR]

The investigation focused on examining the spin polarization and thermal spin polarization transport characteristics of dual rhenium phthalocyanine (Re2PC2) molecular junctions. This analysis was conducted using first-principles density-functional theory and the non-equilibrium Green's function approach. Calculations were performed on molecular junctions in two configurations: one at a non-magnetic electrode (Au) and the other at a magnetic electrode (Ni). A comparison of the spin transport properties of the two electrodes shows significant differences. The magnetic electrode has a notable effect on the spin-polarization and thermal spin-polarization transport properties of the devices. In contrast, the nickel electrode bis-phthalocyanine rhenium molecular device exhibits perfect spin/thermal spin-filtering efficiencies in a parallel structure. The properties of the dual phthalocyanine rhenium molecular devices were significantly affected by the nature of the electrodes. This makes dual rhenium phthalocyanine molecular junctions have great potential for the development of high-performance multifunctional spintronic and spin caloritronic devices. • The nickel electrode Re2PC2 molecular device showed perfect spin/thermal SFE at parallel structure. • PDOS revealed that the transport properties of Re2PC2 molecules were strongly influenced by the magnetic electrode. • Changing the direction of the magnetic moments of the molecules and electrodes can alter the device's characteristics. [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]

We employed first-principles calculations to investigate the structural, electronic, and magnetic properties of carbon/boron nitride nanoribbons in different sizes and doping, using twenty-eight zigzag and armchair configurations. We note that the structures present dynamic stability, with formation energies slightly higher than those of the respective undoped nanoribbons. Our electronic calculations revealed that BN-doped armchair carbon nanoribbons exhibit narrow bandgap semiconductor behavior. Most of the zigzag carbon nanoribbons doped with BN exhibited metallic behavior, in addition to exhibiting non-zero spin polarization in these cases. However, carbon-doped boron nitride nanoribbons in both configurations – zigzag and armchair – exhibited wide-gap semiconductor behavior. We also observed that the energy gap in the band structure directly depends on the doping position. The incorporation of boron and nitrogen pairs into the center of the zigzag carbon nanoribbons does not significantly alter the magnetic properties of the nanoribbons. However, when performed at or near the edges, it results in significant changes in spin polarization. Therefore, based on these results, we can consider potential applications of these nanoribbons in electronic devices. • The studied structures exhibit dynamic stability. • Doping-induced semiconductor behavior. • Band structure is directly influenced by doping position. • Doping with boron and nitrogen in nanoribbons has little impact on magnetic properties. [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]

In this work we report on the systematic characterization of a rare-gas moderated magnetically-transported continuous positron beam based on a 22Na radioactive source. The characterization was performed with three different rare-gas solid moderators: Ne, Ar, and Kr. Each moderator was deposited and then thermal annealed at temperature ∼ 35 % and ∼ 30 % lower than the melting point, respectively. Tests of moderation/magnetic transport efficiency of the apparatus have shown a maximum efficiency of 1.8 10-3, 2.0 10-3 and 0.6 10-3 for Ne, Ar, and Kr, respectively. The average longitudinal kinetic energy of positrons was found to be ∼ 0.95 eV, ∼1.25 eV, and ∼ 0.45 eV for Ne, Ar, and Kr moderator, respectively. The spin polarization measurement of moderated positrons was performed by using the Doppler broadening of the annihilation γ-rays from positronium formed in oxidized nanochanneled silicon positron/positronium converters. Polarization values of 0.30 ± 0.01, 0.29 ± 0.01 and 0.29 ± 0.01 were found for Ne, Ar, and Kr moderator, respectively. [ABSTRACT FROM AUTHOR]

Magnetic tunnel junctions are the core component of spintronic devices, and good magnetic tunnel junctions require high tunnel resistance, which is determined by the spin polarization of the thin films of ferromagnetic layers that make up their structure. Therefore, the design of ferromagnetic films with high spin polarization is a current research hotspot in this field. In the current study, we taken the half-metallic CrYCoAl as an object, and studied the influence of surface effect on the half-metallic behavior. Especially, we constructed the CrYCoAl (100), (110), and (111) surfaces to study their stability, electronic and magnetic properties. Results show that the YY and YAl (100) surfaces, and Co (111) surface retain the half-metallic behavior and structural stability of bulk, which provide a basis for CrYCoAl application as a thin films in magnetic tunnel junctions thus, they are likely to be used in the spintronic devices. • Stability of CrYCoAl (100), (110) and (111) surfaces are estimated by their phase diagrams. • Atomic relaxation and surface roughness are discussed. • Electronic and magnetic properties of CrYCoAl (100), (110) and (111) surfaces are studied. • The YAl and YY (100), and Co (111) termination surfaces maintain the half-metallic nature of bulk CrYCoAl. [ABSTRACT FROM AUTHOR]

Spintronics is a rapidly developing field in advanced technology. It focuses on manipulating the spin of electrons to achieve high-speed data transfer, handling, and storage in order to enhance its capabilities. We conducted a systematic investigation of the ferromagnetism, electronic, and thermoelectric characteristics of spinel compounds LiFe 2 (O/S) 4. Our analysis for optimization demonstrates that ferromagnetic states exhibit great energy release compared to the antiferromagnetic states, indicating the presence of ferromagnetic behavior in the studied compounds. To evaluate the presence of ferromagnetism above room temperature, we employ the Heisenberg model to calculate the Curie temperature and spin polarization to evaluate the presence of ferromagnetism above room temperature. Additionally, a concise overview of the nature of ferromagnetism, including band structures, density of states, exchange energies and constants, hybridization double exchange model, and crystal-field energy, is provided in this research. The absorption of a shift in magnetic moment from Fe to the Li and O/S sites suggests that the ferromagnetic behavior is primarily due to the spin of electrons. Furthermore, we explore the impact of the thermal parameters on the electro-spin as well as the thermoelectric characteristics for both spin-down and spin-up states, providing insights into the energy-harvesting potential. • Half-metallic ferromagentic spinels LiFe 2 (O/S) 4. • Elastic constant are investigated for structural stability. • Electronic and magnetic properties for spintronic applications. • Magnetic moments are discussed for both compounds. • The electronic and lattice thermal conductivity are calculated for thermoelectric characteristics. [ABSTRACT FROM AUTHOR]

Optically pumped atoms have essential applications in magnetic sensing, physics research, and inertial navigation. The polarization gradient caused by light absorption dramatically influences the performance of quantum sensors based on optical pumping. This paper presents a novel approach to address the trade-off between polarization gradient and sensitivity by introducing the pulsed optical pumping method. The interplay of pulsed optical pumping, relaxation, and diffusion processes leads to a more homogeneous distribution of electron spin. Experimental results indicate that the pulsed optical pumping technique increases the optically pumped magnetometer (OPM) signal strength by 12.8% and increases the nuclear spin coherence time by 12.29% in optically pumped co-magnetometer (OPCM). This technology has broad applications in sensors based on the optical pumping effect, such as OPM, OPCM, and nuclear magnetic resonance gyroscope, and holds immense promise for future advancements in the optical pumping field. • Novel Approach: Pulsed optical pumping for homogeneous polarization. • Improved Performance: Improved Performance: Increases OPM signal strength and nuclear spin coherence time. • Broad Applications: Applicable to OPMs, OPCMs, NMRGs, et al. [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 formation energy of Fe2+ in the β-Ga 2 O 3 matrix is lower than that of Fe3+, and the system is more stable when the Ga or O vacancies (V Ga or V O) are adjacent to the Fe lattice position. • The β-Ga 31 Fe2+/3+O 47 and β-Ga 30 Fe2+/3+O 48 systems all exhibit ferromagnetism with above-room-temperature Curie temperature. Ga 30 Fe2+/3+O 48 has more spin-polarized O atoms in the same direction. • The magnetism originates from the double-exchange interaction of the coupling and hybridization of the Fe-3d state of Fe3+ and the O-2p state. • Ga 30 Fe3+O 48 system achieves semi-metallization with 100 % hole spin polarization. Induced by the spin-polarized double-exchange interaction between the 3d orbitals of Fe atoms and O-2p orbitals near the O/Ga vacancy complexes, the origin of magnetism in β-Ga 2 O 3 is investigated by using geometry optimization and energy calculation based on the first-principles generalized gradient approximation Hubbard + U method of density-functional theory. The results show that the formation energy of Fe2+ in the β-Ga 2 O 3 matrix is lower than that of Fe3+, and the system is more stable when the Ga or O vacancies (V Ga or V O) are adjacent to the Fe lattice position. It is found that the β-Ga 31 Fe2+/3+O 47 and β-Ga 30 Fe2+/3+O 48 systems all exhibit ferromagnetism with above-room-temperature Curie temperature. β-Ga 30 Fe2+/3+O 48 (i.e., with Fe2+/3+ and V Ga) has more spin-polarized O atoms in the same direction. The magnetism originates from the double-exchange interaction of the coupling and hybridization of the Fe-3d state of Fe3+ and the O-2p state, which increases the magnetic moment of the β-Ga 30 Fe3+O 48 system. This study provides a theoretical reference for designing and preparing new β-Ga 2 O 3 -based dilute magnetic semiconductors and related spintronic and optoelectronic devices. [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]

[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]

Asymmetric coordination effect is an important concept in heterogeneous catalysis where both catalytic activity and product selectivity are serious influenced. However, this effect has rarely been understood because of the difficult in characterizing detailed coordination information. Here, by employing a theoretical study on electrocatalytic CO 2 reduction reaction (ECO 2 RR) towards HCOOH over Ti 3 C 2 O 2 -based NS/NN co-coordinated transition metal single atom catalysts (TM-NS/NN-Ti 3 C 2 O 2 SACs), we show that asymmetric coordination environments have great impact on the electronic structure of the active center. Both electron transferring ability and spin polarization of the active center are vital to optimize the adsorption and hydrogenation of key intermediates. As a result, both catalytic activity and product selectivity can be maximized. V-NN-Ti 3 C 2 O 2 are predicted to promote high-throughput HCOOH generation process at operation applied potential of −0.32 with considerable electrochemical stability, surpassing most reported catalysts. This work demonstrates V-NN-Ti 3 C 2 O 2 as high-performance ECO 2 RR catalysts, and highlights that the introduction of the concept of asymmetric coordination effect may offer a new insight into the rational design of more efficient SACs. [Display omitted] [ABSTRACT FROM AUTHOR]

We study spin- and valley-dependent transport properties in a n-p–n junction of 8-pmmn borophene monolayer. We show that an exchange magnetic field can generate spin polarization in the system and a gate voltage, as a potential barrier, induces valley polarization. The valley polarization, induced by the gate voltage, is due to the anisotropic and tilted Dirac cones of borophene structure. This property is the advantage of borophene over the other 2D materials with isotropic and non-tilted Dirac cones such as graphene in which a gate potential cannot induce valley polarization. We also show that the proposed device (borophene-based n-p–n junction) can work as perfect spin and perfect valley filters. The spin and valley filters can be controlled by changing the gate voltage and/or Fermi energy. The results of this study show that borophene has a suitable potential to be used in spintronic and valleytronic devices. • Our npn junction can work as perfect spin and perfect valley filters. • Spin-up filter changes to the spin-down filter and vice versa via gate voltage. • Valley filtering by applying gate voltage is due to tilted Dirac cones. • Above property cannot occur in 2D materials with isotropic and non-tilted cones. • Borophene shows a great potential for use in spintronic and valleytronic devices. [ABSTRACT FROM AUTHOR]

An investigation is carried on a quantum system featuring a MoS 2 zigzag nanoribbon employing double magnetic barriers. This study aims to overcome a valley polarization limitation observed in systems using a uniform magnetic field or a single magnetic barrier. A magnetic field breaks the degeneracy of the K and K ′ valleys owing to the valley Zeeman effect, but reversing the direction of the magnetic field is required to invert the valley polarization. In a double magnetic barrier system, interplay between the Fano resonance (arising from the quantum interference between the continuum state of the magnetic barrier and the Landau level) and the resonant tunneling (arising from the quantum states between two barriers) indicates the potential for achieving selective spin and valley polarization by adjusting the strength and width of the magnetic barrier. This can enhance the degree of valley polarization and enable the existence of four distinct spin and valley currents. Obtaining full spin and valley polarization is shown with the optimized parameters of this system. The experimental realization of this system should enable the control of carrier valley and spin degrees of freedom in future devices. [Display omitted] • Three-band tight-binding model using three d orbitals (dx 2 , dx2−y2, and dz2) of Mo atoms. • Double magnetic barrier is used to enhance valley and spin polarization. • Resonant tunneling effect in the K valley and Fano resonance effect in the K ′ valley. • The MoS 2 zigzag nanoribbon system with double magnetic barriers along the same direction has great advantages compared with a single magnetic barrier. [ABSTRACT FROM AUTHOR]

Extreme structure and spin states of doped and undoped perforated bigraphenes was studied using DFT simulations. It was found that folded nanopores possess extremely high curvature of 0.34 Å−1. Dramatic structural deformation causes severe changes of the chemical properties of carbon atoms localized at the nanopores converting the folded edges to local oxidative fragments. It was found that asymmetrical coordination of either Li, Ca, or Al to the nanopores is coupled with electron transfer from metal to edge carbon atoms and breakdown of local inversion symmetry. Li-, Ca-, and Al-doped perforated AA bigraphene revealed ferromagnetic spin ordering with magnetic moments of 0.38, 0.14, and 0.32μ B /unit cell, respectively, and spin polarization energy gain of 0.037eV for Ca-doped superlattice. It was shown that ferromagnetic spin ordering of bigraphene nanopores contradicts to the Nagaoka's theorem, which excludes strong electron correlations as a reason of spin polarization. Spontaneous lift of spin degeneracy was interpreted in terms of perturbing intense local electrostatic fields from extra electron charges localized at the nanopore edges, coupled with breakdown of space inversion and local translation invariances. It was shown that spin energy splitting is proportional to the matrix elements calculated on Bloch states with opposite wavevectors and perturbing electrostatic fields. [Display omitted] [ABSTRACT FROM AUTHOR]

Cost-effective oxygen evolution reaction (OER) electrocatalysts play a key role in electrocatalytic water splitting process. Here, a facile and scalable strategy was applied to synthesize the bimetallic metal-organic frameworks (MOFs) with high OER activity, and the effects of AC magnetic field on OER was also investigated. Results shows that the bimetallic MOFs (Co 0.4 Ni 0.6 -MOF-74) exhibited a three-dimensional flower-like morphology, and possessed a higher BET specific area of 905.39 m2 g−1 as well as a smaller median pore size of 0.49 nm as compared to single metal MOFs; It owned a lowest overpotential of 314 mV at 10 mA cm−2 and Tafel slope of 79.39 mV dec−1, both are much lower than these of single metal MOFs, being due to the high specific area and more active sites derived from the distorted crystal structure; When AC magnetic field strength equaled to 5.50 mT, overpotential at 10 mA cm−2 for Co 0.4 Ni 0.6 -MOF-74 reached minimum value of 201 mV, reduced by about 36% as compared to that without magnetic field, indicated that AC magnetic field could greatly improve OER process. These improvements resulted from the spin polarization effect, magnetohydrodynamic (MHD) convection and improved active point temperature. • Co 0.4 Ni 0.6 -MOF-74 owned a lowest OER overpotential of 314 mV at 10 mA cm−2. • η 10 of Co 0.4 Ni 0.6 -MOF-74 is reduced by up to 36% under AC magnetic field. • Spin polarization, magnetic heating effect and MHD convection improved OER activity. [ABSTRACT FROM AUTHOR]

[Display omitted] One-dimensional (1D) gapless hinge states are predicated in the three-dimensional (3D) higher-order topological insulators and topological semimetals, because of the higher-order bulk-boundary correspondence. Nevertheless, the topologically protected property of the hinge states is still not demonstrated so far, because it is not accessible by conventional methods, such as spectroscopy experiments and quantum oscillations. Here, we reveal the topological nature of hinge states in the higher-order topological semimetal Cd 3 As 2 nanoplate through spin potentiometric measurements. The results of current induced spin polarization indicate that the spin-momentum locking of the higher-order hinge state is similar to that of the quantum spin Hall state, showing the helical characteristics. The spin-polarized hinge states are robust up to room temperature and can nonlocally diffuse a long distance larger than 5 μ m , further indicating their immunity protected by topology. Our work deepens the understanding of transport properties of the higher-order topological materials and should be valuable for future electronic and spintronic applications. [ABSTRACT FROM AUTHOR]

• Highly ordered L2 1 type heusler alloy film on cu substrate. • Near stoichiometric Co 2 FeSn films by electrodeposition. • High magnetic moment, high T C and high effective anisotropy films. • Co 2 FeSn films (320 nm −1400 nm thick) with high crystalline order. • Minority band gap close (∼0.05 eV) to fermi level. Co 2 FeSn films have been electrochemically deposited on polycrystalline Cu substrates in potentiostatic mode. Processed films with thicknesses of 320 nm, 780 nm, and 1400 nm exhibited highly ordered L2 1 type crystal structure with saturation magnetizations of 1023.38 kA/m (5.08 ± 0.04 μ B /f.u.), 1035.31 kA/m (5.14 ± 0.04 μ B /f.u.) and 1044.34 kA/m (5.18 ± 0.04 μ B /f.u.) at 5 K and 965.00 kA/m (4.79 ± 0.04 μ B /f.u.), 967.75 kA/m (4.81 ± 0.04 μ B /f.u.), and 1003.52 kA/m (4.97 ± 0.04 μ B /f.u.) at 300 K, respectively. The soft ferromagnetic films possess coercivity of ∼ 15.92 kA/m (200 Oe) with a high effective anisotropy constant of ∼ 105 J/m3. Thermo-magnetization measurements yielded high Curie temperatures of 995 K, 1005 K, and 1123 K for films of thicknesses 320 nm, 780 nm, and 1400 nm, respectively. Tailoring the thickness from 320 to 1400 nm could be achieved by merely varying the electrodeposition time without appreciable departure from chemical stoichiometry or compromise in crystalline order or magnetic properties. This establishes a methodology to prepare high quality L2 1 ordered Co 2 FeSn films with a few hundred nanometers thickness by electrodeposition. Electrodeposited Co 2 FeSn films with high magnetic moment, high K e f f value, and high Curie temperature are potential candidates for fabricating nanomagnetic devices. [ABSTRACT FROM AUTHOR]

• First-principles calculations performed for XA and L2 1 phases across X 2 FeAl series. • The degree of d-d orbital hybridization drives magnetic and electronic properties. • Increasing X-site valence electron counts result in increased hybridization levels. • Orbital hybridization trends must be considered when predicting material properties. First-principles calculations are performed for full (L2 1) and inverse (XA) Heusler compounds X 2 FeAl, where X comprise a range of 3d (Sc, Ti, V, Cr), 4d (Y, Zr, Nb, Mo), and 5d (Hf, Ta, W) early and middle column transition metal elements. The formation energy difference between full and inverse phase and the degree of d-d orbital hybridization with increasing total valence electron count are shown to drive the magnetic properties (total and atomic magnetic moments, spin polarization) and electronic properties (band structure and projected density of states) of the material system. Specifically, X-site atomic magnetic moments take on increasingly Fe character with increasing valence electron count, in both full and inverse Heusler phases. This can be explained by changes on the degree of d-d hybridization between X- and Fe-site d orbitals. Synchronized energy shifts in the PDOS of the X- and Y-sites (Fe) across each of the full and inverse Heusler series provide us insight to controlling spin polarization via composition. This work demonstrates the need to holistically study the thermodynamic phase stability, magnetic moments, and spin polarization of Heusler alloys, in the framework of anti-site disorder and in a wider compositional context. The end goal of this study is to benefit the mapping of experimental results in search of a specific property, by providing a methodology for extrapolating properties based on experimental or theoretical results. [ABSTRACT FROM AUTHOR]

In this paper, the charge and spin magneto coefficients of a double quantum dots system coupled in series connected to ferromagnetic electrodes with collinear magnetic alignments at finite bias voltage are theoretically investigated based on Green's functions in a linear response regime. Magneto and spin magneto thermopower are estimated as a function of the thermal gradient and quantum dot energy levels. Magneto conductance and spin magneto conductance are also studied. The results showed that the positions of the peaks can be controlled for each value of polarization, and the magneto conductance is negative where the charge conductance for parallel alignment is lesser than that for antiparallel alignment except in the case of high spin polarization and ferromagnetic spin exchange. Enhancing the magneto thermoelectric coefficients of double quantum dots is a promising step in creating adaptable magnetic switching for thermoelectric generations, which could find use in thermal energy-based logic circuits or heat control applications. [ABSTRACT FROM AUTHOR]

The photon-assisted electron transport properties through a parallel-coupled tri-quantum-dot system are studied using the time-dependent non-equilibrium Green's function theory. When a time-dependent external field irradiates a parallel-coupled three-quantum-dot system, the interaction between photons and electrons provides more novel transport characteristics. The average current can be switched between zero and non-zero by controlling the level of the time-dependent external field, indicating that an optically-controlled quantum switch can be realized. The time-dependent external field makes it more advantageous for the system to be designed as a magnetic-controlled quantum switch. If the magnetic flux and Rashba spin orbit coupling interaction are simultaneously considered, the average current exhibits a spin polarization phenomenon. For the spin down current, the bound states are formed as the magnetic flux takes an appropriate value, which greatly enhances the spin polarization. These research results are expected to contribute to the design of future quantum function devices. [ABSTRACT FROM AUTHOR]

Spin-Polarized optical parameters for Sr 2 UFeO 6 double perovskite. [Display omitted] • The Sr 2 UFeO 6 is half-metallic having indirect energy band gaps. • The Sr 2 UFeO 6 to be anti-ferromagnetic with a major contribution from Fe+3. • The Sr 2 UNiO 6 , as ferromagnetic in nature with a major contribution from Ni+6. • The peaks in ε 2 ω are linked to various inter-band transitions. • These double perovskites show substantial absorption in UV region. The electronic, and magneto-optical properties of Sr 2 UXO 6 (X = Fe, & Ni) double perovskite materials, in the monoclinic structure, were calculated employing the full-potential Linearized augmented plane wave (FP-LAPW) approach based on the density functional theory (DFT). The results reveal that Sr 2 UFeO 6 is half-metallic and anti-ferromagnetic, whereas Sr 2 UNiO 6 is semiconducting and ferromagnetic. The spin-polarized linear optical features, including the dielectric functions, absorption coefficients, energy loss functions, reflectivity coefficient, and refractive indexes, have been calculated and analyzed in the energy range of 0–14 eV. The study reveals that both materials exhibit transmission at low energies, making them promising candidates for optoelectronic applications. Moreover, the presence of distinct absorption and reflectivity peaks suggests potential applications in tunable optical devices and sensors. The dispersion characteristics of the refractive index open up new possibilities for developing novel photonic materials. [ABSTRACT FROM AUTHOR]

The spin polarization of current plays an important role in the performance of spintronic devices. Therefore, a highly spin-polarized current source has always been explored through various methods. We study the effects of magnetic order on the electronic structures of antiferromagnetic (AFM) MnBi 2 Te 4 films. A significant spin splitting is found in the surface states of a AFM MnBi 2 Te 4 film with three septuple layers (SLs). The AFM film can show typical metallic behavior for spin-down electrons, and exhibit a semiconductor or insulator behavior with a band gap at the Fermi level for spin-up electrons, just like semimetal ferromagnets with theoretical spin polarization up to 100%. We also study that the electron transport in the 3-SLs AFM film with a square potential barrier, we find a highly spin-polarized current can be switched on and off by modulating the barrier height in the film. • 3-SLs AFM film exhibits a semimetal ferromagnets behavior. • A highly spin-polarized current can be switched on and off by modulating the barrier height. • Gapless surface states induced by magnetic order. • Large spin splitting in spin splitting. [ABSTRACT FROM AUTHOR]

The carrier spin polarization of magnetic materials is one of the most critical elements for current-driven spintronics devices. Experimental evidence of spin polarization of magnetic oxides is still a matter of considerable debate although room-temperature ferromagnetism was reported in nearly all doped/undoped oxides materials. In this work, we systematically study the carrier spin polarization and non-uniform magnetization scattering of Zn 1−x Fe x Al 0.01 O (x = 0.05, 0.10) thin films in metallic regime. Spin polarization 65 ± 8% is confirmed experimentally for Zn 0.95 Fe 0.05 Al 0.01 O by Andreev Reflection spectroscopy, which reduces to 40 ± 5% for Zn 0.90 Fe 0.10 Al 0.01 O as Fe doping level increases to 10%. Magnetoresistance and Anomalous Hall effect are observed in Zn 1−x Fe x Al 0.01 O films which corroborates the spin-polarized carrier in spin-split bands close to the Fermi level. Furthermore, combining element mapping and Andreev reflection spectra, our results support that non-uniform magnetization of Zn 1−x Fe x Al 0.01 O films which introduces large inelastic spin-flip scattering at the interface of Zn 1−x Fe x Al 0.01 O/Pb superconducting junctions, and consequently reduction of spin polarization. The spin-polarized carrier and transport behaviors in Zn 1−x Fe x Al 0.01 O magnetic oxides provide the reliable evidence to identify the intrinsic ferromagnetism and an excellent platform for spintronics device applications. [Display omitted] • Spin polarization of carrier 65 ± 8% was determined quantitatively in Zn 0.95 Fe 0.05 Al 0.01 O thin film for the first time. • Carrier spin polarization and transport offer a reliable evidence to identify intrinsic ferromagnetism of doped oxides. • Element mapping and Andreev reflection spectra, confirm non-uniform magnetization distribution in Zn 0.90 Fe 0.10 Al 0.01 O film. • Ferromagnetism and Anomalous Hall effect of Zn 1−x Fe x Al 0.01 O films corroborate spin-split bands close to the Fermi level. [ABSTRACT FROM AUTHOR]

This paper presents a study on the electronic structure and spin properties of Transition Metal (TM) series doped Black Phosphorus (BP) using density functional theory (DFT) computations. The results indicate that the doped-Cr atom has the lowest formation energy in the BP system compared to other defects. Intrinsic defects do not induce magnetism in the BP material. However, the six types of TM atoms (Ti, V, Cr, Mn, Fe, and Ni) can lead to localized magnetic states in the system. Furthermore, researches on applying strain to the BP system have found that it will induce spin polarization in Co-doped system when applying 8% strain. Magnetic Couplings investigation demonstrate that Fe–Fe interactions exhibit ferromagnetic behavior in the BP system, with a Curie temperature above the room temperature at the d 1 or d 4 distance. These findings are significant to gain deeper insights into material spin polarization and magnetic modulation in functional materials and provide valuable references for the future development of spintronics. • The spintronic properties of transition metals doped black phosphorus were studied systematically. • The magnetic coupling between transition metals is described. • The effect of strain on the electronic structure of the system is revealed. • Our research is beneficial to the development of spintronics. [ABSTRACT FROM AUTHOR]

The magnesium based spinel chalcogenides are outstanding materials for spintronic technology and energy applications. Herein, the modified Becke Johnson potential (TB-mBJ) was employed to investigate the electrical, ferromagnetism, and thermoelectric properties of MgDy 2 (S/Se) 4 spinels comprehensively. The energy emitted during optimization as well as formation energy has both been used to demonstrate the stability of the cubic phase. The density of states, Curie temperature, exchange coupling, and spin polarization are elaborated to address the nature of ferromagnetism. Further, half metallic ferromagnetism is studied in terms of hybridization, exchange energies, and exchange constants. In contrast to the clustering effect of the internal magnetic of Dy atoms in the structure, the lowering of Dy's magnetic moment and its transferring on Mg, and S/Se sites demonstrate that the ferromagnetism is caused by the exchange of electron spin. Furthermore, thermoelectric properties were studied and various thermoelectric parameters such as electrical and thermal conductivities, Seebeck coefficient (S), and power factor (PF) of the examined spinels have been determined. • Above room temperature ferromagnetism, and spintronic applications. • Quantum spin of electrons dominant the charge with multifuctional properties. • Exchange mechanism certifies the ferromagnetism by electron spin instead of magnetic ion clustering. • Half metallic ferromagnetism and 100 % spin polarization. • Large value of electrical conductivity and ultralow low values of thermal conductivity. [ABSTRACT FROM AUTHOR]

• Different edge hydrogenations realize the transition of β -SiC 7 nanoribbons from semiconductors to half-metals to metals. • Spatially separated edge states lead to, arbitrary pairings of upper and lower edge hybridizations are able to diversify the bands near the Fermi level. • The heterojunction H H-zSiC 7 NR-2H H possesses good dual spin filtering properties at low bias and exhibits the NDR phenomenon. Atomic capping is a common approach in edge modification to tune band engineering and can be achieved experimentally through hydrogen plasma etching. Based on first-principles calculations, nine symmetric and asymmetric structures are constructed with different numbers of hydrogen atoms passivated at the edge of β -SiC 7 nanoribbons. An in-depth study reveals that different edge hydrogenations realize the transition from semiconductors to half-metals to metals, firstly, because different numbers of hydrogen atoms lead to different edge atomic orbital hybridizations, and, more importantly and specifically, because the bands around the Fermi level of β -SiC 7 nanoribbons are all derived from the spatially separated edge states, so that arbitrary pairings of upper and lower edge hybridizations are able to diversify the bands near the Fermi level and bring about a richer electronic properties. We also design the metallic H-zSiC 7 NR-H and semiconducting 2H-zSiC 7 NR-H into a heterojunction, which possesses good dual spin filtering properties at low bias, can achieve a spin polarization transition from -100 % to 100 %, and exhibits the NDR phenomenon. These findings suggest that β -SiC 7 nanoribbons have promising applications in the field of spintronics. [ABSTRACT FROM AUTHOR]

• The half metallicity of NiVTiZn could be maintained when uniaxial strain ratio increases from −7.28% to 9.59% and when c / a ratio ranges from 0.92 to 1.06. • The 100% spin polarization is preserved in V(Ti), Ni-Zn and V-Ti disordered structures. • The effect of various disorder on mechanical and thermodynamic properties is also studied in detail. The influence of atomic disorder on electronic, mechanical and thermodynamic properties of equiatomic quaternary all- d metal Heusler alloy NiVTiZn is studied by employing the first-principles calculations. The ground state of NiVTiZn is confirmed to be α -type structure with ferromagnetic nature, the calculated spin down energy gap and equilibrium lattice constant is ∼0.7 eV and 6.048 Å, respectively. The half metallicity could be maintained when uniaxial strain ratio increases from −7.28 % to 9.59 % and when c / a ratio ranges from 0.92 to 1.06, showing a robust half metallicity against the strain effect and tetragonal distortion. Six types of atomic swap disorder and twelve types of atomic antisite disorder are proposed. The V(Ni) and V(Zn) antisite disorders as well as V-Ni and V-Zn swap disorders are the most favorable owing to their negative formation energies. The 100 % spin polarization is preserved in V(Ti), Ni-Zn and V-Ti disordered structures although the width of band gap suffers contraction. The spin polarization of Ni(V), Ni(Zn), V(Zn) and Zn(Ni) disordered structures is also larger than 80 %. In addition, the effect of various disorder on mechanical and thermodynamic properties is also studied in detail. [ABSTRACT FROM AUTHOR]

In this theoretical study, we investigate novel quaternary Heusler Fe–Rh–Mn–Al alloys in the X-type structure with different types of atomic ordering in the unit cell within the spin-polarized density functional calculations. The calculations showed that the 24 possible configurations converge to the 6 nonequivalent solutions. Two types of atomic ordering with the lowest total energy Fe(4c)Rh(4d)Al(4b)Mn(4a) and Mn(4c)Al(4d)Fe(4b)Rh(4a) are half-metallic ferrimagnets in which the spin polarization at the Fermi level is close to 100 %. However, no gap is open in the majority spin projection. The following values of the total magnetic moments for these alloys were obtained: 3.01 and 3.19 μ B /f.u., respectively. In the other types of atomic ordering, the half-metallic state is not formed. In FeAlRhMn, the magnetic moment on the manganese ion compensates for the moments on the other ions, and the total moment is close to zero. In the types (MnFeRhAl, AlRhFeMn) of atomic ordering with high energies, the metallic state is also realized, and the magnetic moments on the ions are ordered ferrimagnetically. In this work, we analyzed novel quaternary alloys with different types of atomic ordering motivated by the demand for alloys with a high spin polarization, among which the FeRhAlMn and MnAlFeRh alloys were found. Both with a half-metallic ferrimagnetic state and the lowest total energy among these alloys with the same chemical composition, which indicates the stability of the half-metallic state. The other types of atomic ordering are less energetically favorable, those alloys are ferrimagnetic metals with the low spin polarization. Taking into account the half-metallic state and high spin polarization, the quaternary FeRhAlMn and MnAlFeRh alloys have prospects for use in spintronic devices. [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]

• Property of multicomponent soft magnetic alloy was predicted by first-principles calculation. • Complex competition exists among Fe, Ni, and Cr in affecting physical properties. • Relatively high contents of Fe and Cr is expected for great electromagnetic performance. • Ni is beneficial to enhancing the system stability of the face-centered cubic structure. • This work give a strategy for accelerated design of multicomponent soft magnetic alloy. Multicomponent alloys (MCAs) exhibit excellent soft magnetic properties and other service performance, and are promising for high-end applications. However, their complicated effects of element mixture and low efficiency in research and development could limit their industrialization. Hence, in this work, first-principles calculation was conducted on the relative formation energy, magnetism and density of states of Fe-Ni-Cr-Si-P-B-C-Nb MCAs for predicting its alloy stability, saturation magnetization (B s) and electric resistivity (ρ). The calculation results mainly present the mixture effects among Fe, Ni and Cr. There is a complex competition among Fe, Ni, and Cr elements in affecting the physical properties of the MCAs. The magnetism of the MCAs is not only determined by composition of magnetic elements but also by the coordination environment around the magnetic atoms. To achieve both high B s and high ρ in the Fe-Ni-Cr-Si-P-B-C-Nb system, proper addition of Fe and Cr may be expected. The optimized MCA has a relatively high B s nearly equal to the Fe-Si-Al system, and exhibits higher ρ and higher spin polarization. This indicates that the proposed MCAs are promising for both power devices and spintronic applications. This work gives a strategy for the property prediction and accelerated design of MCAs by first-principles calculation. It has promising potential to explore other element systems as for high-performance soft magnetic MCAs. [ABSTRACT FROM AUTHOR]

We consider a film of a topological insulator (TI) sandwiched between two ferromagnetic (FM) layers. The system is additionally under an external gate voltage. The surface electron states of TI are magnetized due to the magnetic proximity effect to the ferromagnetic layers. The magnetization of ferromagnetic layers can be changed by applying an external magnetic field or by varying thickness of the topological insulator (owing to the interlayer exchange coupling). The change in the magnetic configuration of the system affects the transport properties of the surface electronic states. Using the Green function formalism, we calculate spin polarization, anomalous Hall effect, and magnetoresistance of the system. We show, among others, that by tuning the gate voltage and magnetizations of the top and bottom FM layers, one can observe the topological transition to the quantum anomalous Hall state. • A topological insulator sandwiched between ferromagnetic layers is considered. • Two magnetization configurations of layers (parallel and antiparallel) are studied. • Switching between trivial and topological insulator state under gate voltage is discussed. [ABSTRACT FROM AUTHOR]

Spintronic is the developing technology which probes the properties of quantum devices with spin of electrons which reduce the size and enhance its speed. Therefore, here the role of 5d electrons and thermoelectric characteristics of double perovskites (DPs) K 2 ZCl/Br 6 (Z = Ta, W, Re) elaborated comprehensively by density functional theory (DFT). The Heisenberg model spin polarization density (SP) has been applied to evaluate the Curie temperature (T c) and spin polarization factor. The tolerance factor (t F) and formation energy (ΔH) have been calculated to confirm the stability of structures. Ferromagnetism has been discussed in terms of spin polarization, crystal field energy (Δ CF) and exchange energies (Δ(d), Δ(pd)). The double exchange mechanism, and exchange constants ensure the role of electrons spin in ferromagnetism instead of segregation of transition metal ions. The transferring of magnetic moments of transitions metals to nonmagnetic sites (K, Cl, Br) show the exchange of spin of electrons and integer values of total magnetic moment show 100 % spin polarization. Finally, the transport properties are studied in standings of electrical and thermal conductivities. The large value of Seebeck coefficient and power factor ensure the importance of studied DPs for thermoelectric generators. • Spintronic and energy harvesting applications. • Large value of Curie temperature and high spin polarization. • The ferromagnetism by electron spin instead of magnetic ion clustering. • Half metallic ferromagnetism evidence complete spin polarization. • Ultralow low values of thermal conductivity and Large power factor. [ABSTRACT FROM AUTHOR]

The spin-interdependent transport features for phosphorene superlattice, containing spin-flip and spin polarization are described under a constant electric field and extrinsic Rashba spin-orbit interaction utilizing the transfer matrix method. Our findings demonstrated the number of barriers at this structure acts the prominent role at the spin polarization and transmission probability, that can be applied in modeling optimum spintronic apparatus. Interestingly, the best outcomes for the transmission probability and spin polarization transpired in the five obstacles. Furthermore, an incoming electron with spin-up (down) can be transferred as an electron with spin-down (up) by adjusting the bias voltage and Rashba strength. Our findings can be utilized to create new nanostructures and maximize the performance of spintronic systems based on phosphorene nanoribbons. • The spin- independent transport features for a phosphorene superlattice, containing spin-flip and spin polarization have been studied under a constant electric field and extrinsic Rashba spin-orbit interaction utilizing the transfer matrix method. • The barriers number in the superlattice structure plays a dominant role in the spin polarization and transmission probability, that can be applied in modeling optimum spintronic apparatus. • By tuning the strength of external Rashba strength, and the bias voltage, it is possible to accurately control the conductance properties of the system and achieve high conductance which can be used in nano-electronic circuits and semiconductor devices. • The results show that by controlling the Rashba strength and the bias voltage, Spin Flip occurs. [ABSTRACT FROM AUTHOR]

Trilayer graphene exhibits valley-protected gapless states when the stacking order changes from ABC to CBA and a gate voltage is applied to outer layers. Some of these states survive strong distortions of the trilayer. For example, they persist when the outer layers are partially devoid yielding a system of two trilayers of different stacking order connected by a strip of a single graphene layer. Here we investigate how these states respond to another perturbation, i.e., the presence of magnetic defects, which we model as π -vacancies. We show that the gap states hybridize with the defect states and strongly spin-split. More importantly, it is demonstrated that by changing the gate voltage value one can change the spin density of the gap states and the corresponding currents at the Fermi level. [ABSTRACT FROM AUTHOR]

Semiclassical expansion of the Wigner function for spin- 1 2 fermions having an effective spacetime-dependent mass is used to analyze spin-polarization effects. The existing framework is reformulated to obtain a differential equation directly connecting the particle spin tensor with the effective mass. It reflects the conservation of the total angular momentum in a system. In general, we find that the gradients of mass act as a source of the spin polarization. Although this effect is absent for simple boost-invariant dynamics, an extension to non-boost-invariant systems displays a non-trivial dependence of the spin density on the mass indicating that the spin polarization effects may be intertwined with the phenomenon of chiral restoration. [ABSTRACT FROM AUTHOR]

We study the effects of torsion as predicted by the Einstein-Cartan theory in the test-particle non-relativist approximation. We derive the corresponding 2-spinor Hamiltonian. Then, we solve an idealized reflection and transmission problem for a beam travelling across a spin-polarized target. We identify deviations in the spin polarizations on the reflected and transmitted beams that can distinguish Einstein-Cartan from general relativity. These deviations would constitute compelling evidence for a non-trivial spacetime torsion if measured. [ABSTRACT FROM AUTHOR]

A model-independent irreducible tensor formalism is developed to analyse Ω ¯ Ω production in p ¯ p collisions and its subsequent decay via the triple-strange decay process, Ω ¯ + Ω − → K + Λ ¯ K − Λ → K + p ¯ π + K − p π −. These processes are relevant for the upcoming experiments at PANDA. We not only provide expressions for the density matrix of the Ω Ω ¯ system but also for the products at each stage of the decay. The Fano statistical tensors so obtained not only completely characterize the relevant final systems but also provide expressions for joint angular distributions. Finally, we show which of the Fano statistical tensors characterizing the Ω ¯ Ω system can be inferred from the Fano statistical tensors characterizing the final p ¯ p system, wherein we also obtain the relation between the production cross sections for Ω Ω ¯ and the final p p ¯ system. [ABSTRACT FROM AUTHOR]

The basis of spintronics is the technology involving nano-sized devices whose spins are directed. Therefore, materials that provide magnetic and 100 % spin polarization are remarkable. The ferromagnetic phase of VCo 2 O 4 has obtained the most stable. In the GGA approximation, the equilibrium lattice constant and magnetic moment values were 8.34 Å and 10.00 μ B /f.u., respectively. The band gaps in the GGA and GGA + mBJ approximations were calculated as 1.262 eV and 4.847 eV. The band gap values for Coulomb interactions U = 1, 2, 3, and 4 eV were obtained as 1.268 eV, 1.273 eV, 1.279 eV, and 1.286 eV, respectively. The elastic calculations showed that VCo 2 O 4 was mechanically stable and ductile. The Debye temperature was calculated as 565 K at 0 GPa pressure. As a result, VCo 2 O 4 oxide spinel has been obtained as a true half-metallic ferromagnetic material and will be a very good alternative for spintronic applications. [ABSTRACT FROM AUTHOR]

Density of states and band structures reveals 100% spin polarization and half metallic ferromagnetism. [Display omitted] • The Half metallic ferromagnetism, and spintronic applications. • Magnesium ion battertties and energy storage. • The ferromagnetism due to electron spin as an alternative of magnetic ion clustering. • Above room temperarue Curie temperature and 100% spin polarization. • Ultralow low thermal conductivity and Large value of electrical conductivity. The ferromagnetism due to rare earth elements-based spinel chalcogenides has become emerging aspirant for spintronic devices. Therefore, theoretically computed electronic properties of MgTb 2 (S/Se) 4 spinels are analyzed to comprehend the structural, magnetic, and thermoelectric characteristics. Thermodynamic stability is elucidated using the computed enthalpy of formation (ΔH), phonons dispersion band structures. Using structural optimizations, difference in the energy states has revealed the ferromagnetic (FM) state stability. The computed band structures (BS) and density of states (DOS) both depict a half-metallic ferromagnetic state exhibiting a net spin polarization at the Fermi energy level. The underlying ferromagnetic state has been suggested due to carrier mediated indirect RKKY exchange mechanism. The thermoelectric properties are calculated to evaluate their potential for wasted-heat to useful-electricity conversion applications. The small thermal conductivity, and high-power factor exhibited by MgTb 2 S 4 at room temperature suggest it significant for applications in thermoelectric generators. [ABSTRACT FROM AUTHOR]

[Display omitted] • First-principles analysis to determine the impact of lanthanum (La) at the A-site and X (Ni, Co, Mn, Ti) at the B-site as mono- and co-dopants on spin-polarized electronic, structure and magnetic characteristics of Cubic BFO structure. • Calculations carried out in the Cambridge Serial Total Energy Package (CASTEP) code by using ultra-soft pseudopotential (USP) under GGA and LDA + U functionals. • The substitution of La and X atoms alters the spin-polarized electronic and dielectric characteristics of BFO, leading to an increase in the density of states (DOS) around the Fermi level. • LaCo and LaNi have shown have high spin polarizations of 87.08% and 82.20%. • Extremely low switching energies of 0.52 aJ and 0.72 aJ, respectively, observed for LaCo and LaNi co-doped BFO systems. In spintronic technology, bismuth ferrite BiFeO 3 (BFO) is a potential multiferroic material for multiferroic capacitor application. In present study, the impact of transition metals X = Co, Ni, Mn, Ti at the Fe-site and rare earth element lanthanum (La) at the Bi-site is investigated using DFT calculation in order to improve the structural stability, spin polarized electronic, and dielectric properties of bismuth ferrite for switching energy of multiferroic capacitor applications. The calculations are carried out in the Cambridge Serial Total Energy Package (CASTEP) code by using ultra-soft pseudopotential (USP). The substitution of La and X atoms alters the spin-polarized electronic and dielectric characteristics of BFO, leading to an increase in the density of states (DOS) around the Fermi level. The observed descending order of the structure stability of co-doped BFO is given as: LaCo > LaNi > LaMn co-doped BFO system. LaCo and LaNi co-substituted systems have shown high spin polarizations of 87.08 % and 82.20 % respectively. Low switching energies of 0.52 aJ and 0.72 aJ, respectively have been observed for LaCo and LaNi co-doped BFO systems for multiferroic RAM capacitor applications. [ABSTRACT FROM AUTHOR]

A high degree of spin polarization in half-metallic double perovskites is a prerequisite for several applications in spintronics, which depends crucially on the cationic order of the systems. This paper reports a study on tailoring the structure and morphology of nano-sized Sr 2 Fe 1- x Zn x MoO 6 (x = 0.05, 0.1, 0.15) materials to improve their spin polarization. The combined analysis of synchrotron X-ray diffraction and magnetization data shows that Zn replaces Fe in the B sites. Although the majority of particles have lateral dimensions in the range 30–60 nm as observed by scanning electron microscope, the samples with x = 0.1 and 0.15 show finite-size effects with superparamagnetism below room temperature and a reduced Curie temperature (from 410 K for x = 0.05–390 K for x = 0.15). The results are due to the formation of networks of insulating Mo–O–Zn–O–Mo linkages and anti-phase boundaries, which divide the particles into smaller domains with a mean diameter of ∼11 nm as determined via a Langevin fit. The almost perfectly ordered structure in the nanodomains is responsible for a high magnetoresistance ratio. A value of -42% at 5 K in 50 kOe is recorded for the sample x = 0.15. Via fitting the magnetoresistance curve using the Inoue-Mekagawa theory, the spin polarization of 99% is determined. [ABSTRACT FROM AUTHOR]