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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]

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]

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]

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]

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]

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]

The effective mass of holes (m ∗) in GaAs quantum wells is investigated as a function of spin polarization, temperature, and carrier density using the Hartree–Fock approximation. The results reveal m ∗ initially decreases at low carrier densities before increasing with density. Additionally, as the interaction parameter increases, m ∗ decreases rapidly. Especially, as the temperature rises to 200 K, m ∗ asymptotically approaches a value of 0.45 m 0 , where m 0 is the electron mass. These findings provide insights into the influence of Coulomb interaction and exchange energy on the effective mass of semiconductors across a wide range of temperatures, spin polarizations, and densities. • Spin, temperature, and carrier density dependence of hole effective mass in quantum well is analyzed. • Majority mass increases with spin polarization while minority mass decreases. • Majority mass has a clear minimum at low every temperature an at low carrier density below 2 × 1010 cm−2. • The results are consistent with experimental results. [ABSTRACT FROM AUTHOR]

We report the structural stability and half-metallicity of the half-Heusler alloy CoMnSe via the density functional theory (DFT). The γ -phase ferromagnetic of CoMnSe is more energetically stable than other phases. The electronic and magnetic properties show that the CoMnSe is a false half-metal ferromagnetic with 98.10% spin polarization and a total magnetic moment of 4 μ B . This value is in good agreement with the Slater-Pauling rule and available data using the GGA method, whereas the GGA+U method shows it is a ferrimagnetic metal with 95.73% spin polarization, and the total magnetic moment is 4.01 μ B. The effects of Bulk strain and axial strain demonstrate that the relative change of total magnetic moment M t o t and spin polarization P of CoMnSe is almost negligible, indicating that the half-metallicity is strong against Bulk strain and axial strain. Using Monte Carlo simulations, a transition ferromagnetic-paramagnetic response is also studied. • CoMnSe alloy is mechanically and thermodynamically stable. • CoMnSe does not undergo martensitic transformation. • CoMnSe is found to be falsely half-metallic using GGA, while it is metallic using GGA+U. • The high spin polarization and Curie temperature make CoMnSe suitable for spintronic. [ABSTRACT FROM AUTHOR]

Silicon (Si) is the dominant material in the semiconductor industry with some novel properties, the introduction of germanium (Ge) and vacancies lead to special electronic and magnetic properties. In this work, the effects of spin-polarized electrons regulate the electronic and magnetic properties for substituted Ge in bulk crystalline Si (Ge Si) with vacancies and electrical charge states introduced are investigated based on first-principles calculations. It is found that the electron spin density of Ge-vacancy (GeV) and Ge-divacancy (GeV 2) complex structures is redistributed, the number of the defect energy levels is changed, and the magnetic moment on atoms appears when vacancies are introduced in Ge Si. In addition, the distribution of the defect energy levels in the band gap is affected by charge states (negative and neutral), resulting in changes in the degree of spin-splitting, orbital occupation and electron filling, energy levels degeneracy, and the magnitude of the magnetic moment. These results show that the spin polarization on Ge Si with vacancies and charge states, the number and the distribution of the vacancies around Ge, all play important roles in regulating the magnetic moments, magnetic properties, and the magnitude and distribution of defect energy levels. [ABSTRACT FROM AUTHOR]

In the present work, structural, electronic, magnetic, elastic, mechanical, thermal and optical properties of XCrAl (X = Fe, Co, Ni, Cu) Half-Heusler (H–H) alloys were explored. First-principles study based on the non-polarized and spin-polarized density functional theory (DFT) were employed to get the geometrically relaxed unit cell structures of H–H alloys of investigation. The larger lattice constant values were found due to the spin polarization and the magnetic moments were calculated from the spin density of states (DOS). The higher values of magnetic moments make XCrAl alloys suitable for magnetic device applications. The computational electronic structure analyses at zero applied pressure confirm the zero energy band gap of XCrAl alloys which displayed metallic nature for all the compounds. From the elastic constants calculations, all the studied alloys were found mechanically and thermally stable. The values of melting temperatures were obtained in the range from 2072 to 1883 K and the calculated Debye temperatures followed the same manner of variation. Among the studied compounds, FeCrAl exhibits highest melting temperature and lattice thermal conductivity with the value of 12.94 Wm−1K−1 at 300 K which is in good agreement with the other reported results. These investigations suggest that, FeCrAl is relatively more suitable in accident-tolerant fuel (ATF) cladding material applications over the common Zr-based cladding rods. The frequency dependent optical properties of the studied H–H alloys were also explored comprehensively and the examinations indicate that, XCrAl (X = Fe, Co, Ni, Cu) alloys can also be the good choice for ultraviolet (UV) based optical device applications as they have high absorption coefficient of >200 × 104 cm−1 and maximum reflectivity of >94% in the UV region. • The physical properties of XCrAl (X= Fe, Co, Ni, Cu) half-Heusler (H-H) alloys were studied comprehensively by DFT based first-principles study. • The structural relaxation was done by the geometry optimization at zero applied pressure. • The metallic nature for all the studied compounds is obtained from band structure and density of states (DOS) calculations. • The elastic, mechanical and thermal stabilities were successfully investigated and high melting temperatures were found. • Among the studied alloys, FeCrAl is found more suitable for high-temperature applications and XCrAl H-H alloys also possess interesting optical responses in the ultraviolet (UV) region. [ABSTRACT FROM AUTHOR]

We present our work on the structural, electronic and magnetic properties of monolayer-CdS which was subjected to bi-axial strain and hydrogenation at possible adsorption sites using the first-principles calculations. The results show that both bulk-CdS and monolayer-CdS are non-magnetic direct (Γ − Γ) band-gap semiconductors. By applying a compressive strain up to −10 % the monolayer-CdS remain direct band-gap semiconductor with a maximum band gap value of 2.11 eV. In contrast, a semiconductor to metal transition occurred at 17 % applied tensile strain. Moreover, hydrogenation on all possible adsorption sites induces ferromagnetism and p -type conductivity in monolayer-CdS. Among all possible adsorption sites, H added on the Cd-top site is the most probable site showing strong ferromagnetism and half-metallicity. The strong ferromagnetism means 100 % spin polarization is retained up to applied bi-axial strain of −5 % to +15 %. Also, half-metallicity is robust under the bi-axial strain in the range of −4 % to +2 %. To determine the strength of the exchange-coupling parameter, the FM (ferromagnetic) and AFM (anti-ferromagnetic) coupling between added atoms was investigated under the bi-axial strain of −5 % to + 5 %. Our findings show that H added on the Cd-top site makes it ferromagnetic and half-metallic above room temperature. The maximum Curie temperature T c = 651.41 K is achieved at a strain of ɛ = −2 % of ferromagnetic state. This high Curie temperature has not been achieved for any 2D material to-date. The present work provides a route to harness the ferromagnetism and thermal stability of 2D monolayer-CdS for electronic and spintronic applications. [ABSTRACT FROM AUTHOR]

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

The g-C 6 N 6 is a semiconductor material, the effect of this material used in electronic and microelectronic devices is far from reaching the expected effect. To improve the overall performance of g-C 6 N 6 , this study decided to cut g-C 6 N 6 for nanoribbons. It was found that g-C 6 N 6 nanoribbons could not be directly used in electronic devices and microelectronic devices through first principles calculation. In order to change its properties, it was decided to adsorb two different transition metal atoms Fe and Mn in the g-C 6 N 6 nanoribbons, respectively. The results show that g-C 6 N 6 nanoribbons have magnetic properties after adsorbing transition metal atoms, and the two structures have spin polarization phenomena after adsorption of Fe and Mn atoms. Their energy band, density of states (DOS) and the charge density after the adsorption of transition metal atoms were analyzed. The results show that g-C 6 N 6 nanoribbons becomes an indirect narrow band gap semiconductor by adsorbing different transition metal atoms, which improves the performance of g-C 6 N 6 nanoribbons. Through computational molecular dynamics simulation, g-C 6 N 6 nanoribbons can exist stably in a real environment. Our research provides theoretical support for the application of such materials in spintronics devices and optoelectronic devices. • The g-C6N6 nanoribbons generate magnetism by adsorbing transition metal atoms. • The g-C6N6 nanoribbons adsorb transition metal atoms become indirect narrow band gap semiconductor. [ABSTRACT FROM AUTHOR]

In this paper, we study the spin polarization of stationary and moving bright solitons in spin orbit coupled Bose Einstein condensate trapped by a variable shape optical lattice. We particularly investigate the effects of optical lattice parameters, detuning parameter and spin orbit coupling strength on spin polarization. We find that the spin polarization may show different characteristics in different regions of the potential. We also study the dynamical properties of moving bright solitons which change significantly with the optical lattice parameters. The study is performed by using the variational and numerical methods. • Solitons in a variable shape optical lattice potential are investigated. • The parameters effecting the spin polarization are reported. • The dynamical properties of solitons change with the optical lattice parameters. [ABSTRACT FROM AUTHOR]

We use the technique of time-resolved Kerr rotation (TRKR) to measure the electron spin polarization generated by optical spin pumping in an n-type gallium arsenide (GaAs) epilayer when an external electric field is simultaneously applied on the sample. The drift of the electron spins under the influence of the external electric field is captured with spatial scans of the pump–probe separation. A significant decay in the magnitude of electron spin polarization with electric field is observed and is attributed to the increased inhomogeneous broadening caused by the field-induced drift and the hot electron effects. We extend the electric field range to as high as the Gunn threshold field in the measurement and we do not observe a spin amplification effect due to the spin Gunn effect under our experimental scheme. • Optical pump–probe technique is used to study electron spin polarization in n-GaAs. • E-field dependent spin drift and spin decay are measured in spin drag experiments. • Spin decay and amplification effects at E-fields at Gunn threshold regime are probed. [ABSTRACT FROM AUTHOR]

A detailed experimental and theoretical investigations on the origin of room temperature ferromagnetism in Fe doped CdS diluted magnetic semiconductor is reported in the present study. X-ray diffraction results reveal the cubic zinc blende CdS structure with an average crystallite size of 2 nm–3 nm which is in concurrence with the Transmission electron microscopy results. UV–visible spectroscopy depict the enhancement of optical band gap of Fe doped CdS nanoparticles compared to the bulk CdS as a result of the quantum confinement effect. Photoluminescence spectra revealed the presence of Cd2+ and S2− defect states in the nanoparticles in addition to the fluorescence quenching effect. FTIR results demonstrate the stretching vibrations of Cd S bond. Magnetic study confirms the existence of room temperature ferromagnetic ordering in the nanoparticles for the lower concentration of Fe, as a result of spin polarization induced by the Fe atoms to the nearest neighboring S atoms. At higher concentration of Fe, the enhanced antiferromagnetic interaction between short range Fe ions suppresses the ferromagnetic ordering. Theoretical calculations demonstrate the half metallic nature of Fe doped CdS system with strong p-d hybridization between the Fe-d states and the S-p states which results the room temperature ferromagnetism. • DFT calculations are performed to investigate the ferromagnetic ordering in the Fe doped CdS nanoparticles. • Fe doped CdS system shows half metallic properties. • The ferromagnetic ordering is due to p-d exchange interaction between the localized d spins of the Fe ions and the free delocalized carriers. • p-d hybridization between the d states of Fe and the p states of S are observed in the Fe doped CdS system. [ABSTRACT FROM AUTHOR]

We report the magnetic behavior of isolated Fe impurity atoms in Pd 1− x U x (0 ≤ x ≤ 0.12) alloys studied through measurements of the local susceptibility (χ loc) and spin relaxation time for 54Fe nuclear probe using the time differential perturbed angular distribution (TDPAD) technique. With an increase of the U concentration in Pd-U alloys, the magnetic response of Fe, exhibiting Curie-Weiss type χ loc (T), reflects a steady decrease of the giant magnetic moment arising from ferromagnetic polarization of host Pd-4d band electrons. Concomitantly, we find an exponential rise in the spin fluctuation temperature T SF. The experimental observation of U induced suppression of giant magnetic moment of Fe in Pd is supported by ab intio electronic structure calculations based on density functional theory. The results presented here support the idea that sign and strength of spin polarization of host conduction band electrons play a crucial role on the spin fluctuation rate and hence moment stability. • Fe shows Curie-Weiss type local susceptibility in Pd-U binary alloys. • Exponential rise in Spin fluctuation temperature T SF with Uranium concentration. • The sign and strength of spin polarization of host conduction band electrons play a major role in the spin fluctuation rate. • Beyond x = 0.12 (Pd 1− x U x), the Fe atoms become nonmagnetic due to large spin fluctuation. [ABSTRACT FROM AUTHOR]

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

This manuscript reports the theoretical results on the magnetic and electronic properties of the new rare-earth element based LuCoVGe equiatomic quaternary Heusler (EQH). To investigate the magnetic and electronic properties of this compound, we used the both Methods: The first-principles calculations using Quantum Espresso and the Monte Carlo simulations (MCS). The good properties of LuCoVGe alloys that is, large half-metallic gaps and 100% spin polarization fulfill the requirements of the candidate materials for diverse applications especially in spintronics. A clear behavior of half-metallicity appearing in the First principles calculations when to investigate the density of states (DOS) and band structure of the Heusler compound LuCoVGe. On the other hand, for non-null temperature values, the behavior of the total magnetizations are presented as a function of the temperature, exchange coupling interactions, crystal field and the external magnetic field. Finally, we outlined and talked about the hysteresis loops as a function of the external magnetic field, when settling the values of the examined physical parameters. • The Heusler LuCoVGe is studied. • DFT and Monte Carlo simulations are used. • The hysteresis loops are presented. [ABSTRACT FROM AUTHOR]

Abstract The structural, mechanical, electronic and magnetic properties of quaternary Heusler ZrTiRhGa alloy have been investigated by using the first-principles calculations within the generalized gradient approximation GGA. The results of our calculations show that the type (I) of ZrTiRhGa, with the ferromagnetic (FM) state, is the most stable configuration among three possible configurations. The GGA + U calculations, where U is on-site Coulomb interaction correction, are performed to investigate the relationship between band gap and Hubbard potential. The calculated results showed that ZrTiRhGa compound is half-metallic material (HMM) with complete spin polarization around the Fermi level. The total magnetic moment is 2 μB per formula unit and follows the Slater-Pauling rule μt = Zt−18. The calculated elastic constants, cohesive and formation energy, for ZrTiRhGa compound, were analyzed in detail and reveal the mechanical stability. In addition, we investigated the sensitivity of the half-metallicity with two structural-type changes: hydrostatic and tetragonal deformation. Our calculations show that the half-metallicity can be preserved with lattice constants from 5.74 Å to 7.12 Å, under the influence of hydrostatic strain and in the range of the c/a ratio from −8% to 12% with the effect of the tetragonal strain. For ZrTiRhGa, since there is no available experimental data, our calculations are considered as first predictions. Highlights • The quaternary Heusler ZrTiRhGa alloy has HM nature at the equilibrium volume. • The calculated Mtot of quaternary Heusler ZrTiRhGa alloy is 2 µB, which is in agreement with Slater- Pauling rule. • ZrTiRhGa alloy maintains the HM nature when the values of lattice constant are included between 5.74 Ǻ -7.12 Ǻ. • The quaternary Heusler ZrTiRhGa alloy maintains the HM nature, in the range of the c/a ratio from 0.81 to 1.2. [ABSTRACT FROM AUTHOR]

Abstract The inverse Heusler alloy Zr 2 RhAl is investigated using first-principles calculations. The calculations are carried out using the full-potential linearized augmented plane wave plus local orbital (FP-LAPW + lo) method that is employed in the WIEN2k package. The structural, electronic, magnetic, and thermoelectric properties are studied. It is found that the ferromagnetic phase of Zr 2 RhAl is the most stable with lattice parameter 6.6328 Å. The calculations showed that there is an energy gap in the spin down channel whereas the spin up channel is metallic, resulting in a 100 % spin polarization at Fermi level. This is an obvious characteristic of half-metallic materials. The calculated total magnetic moment of Zr 2 RhAl is found to be 2 μ B which follows the generalized Slater-Pauling rule. The Curie temperature is estimated to be 607 K using the mean field approximation. Transport properties are studied using the Boltzmann theory with constant relaxation time approximation. The variation of transport properties with temperature is investigated using the two current model. Highlights • The ferromagnetic phase of Zr 2 RhAl is the most stable magnetic phase. • The Zr 2 RhAl have metallic behavior for spin–up channel and a semiconducting behavior for the spin down channel with band gap 0.50635 eV. • The Curie temperature of Zr 2 RhAl was found to be 607 K within the mean field approximation. • The transport properties for the spin-down channel show promising future for thermoelectric applications. [ABSTRACT FROM AUTHOR]

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

This study focuses on new diluted magnetic semiconductors that have good characteristics. The chemical compound we use in this paper is Mg 1-x Cr x S (x = 0,0, 0.125, 0.25, 0.50, 0.75) at the ferromagnetic rock salt phase, We used the linearized augmented plane wave method implemented in the wien2k package to simulate compound properties and adopted the WC-GGA approximation to calculate structural and elastic properties and the Tb-mBJ approximation (Tran-Blaha modified Becke-Johnson potential) to calculate electronic, and optical properties. The results obtained prove that the ferromagnetic (FM) phase is more stable than the antiferromagnetic (AFM) and nonmagnetic (NM) phases, the energy band of all ternary compounds Mg 1-x Cr x S has been shown to be half-metals with a 100% spin polarization at the Fermi level (E F) and total magnetic moment values equal to 4 μB. The study reported that the elastic properties of Mg 1-x Cr x S (x = 0.125, 0.25, 0.50, 0.75) compounds are mechanically stable with high mechanical anisotropy. The optical spectra of ternary compounds Mg 1-x Cr x S (x = 0.125, 0.25, 0.50, 0.75) are distinguished from those of MgS by the appearance of additional absorption at low energy. The compounds are dispersive media that show strong absorption in the ultraviolet radiation region observed on the α (ω) curve. [ABSTRACT FROM AUTHOR]

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

We extend the spin-polarized effective-interaction approximation of the parquet renormalization scheme from Refs. [1,2] applied on the symmetric Anderson model by adding the low-temperature asymptotics of the total energy and the specific heat. We calculate numerically the Wilson ratio and determine analytically its asymptotic value in the strong-coupling limit. We demonstrate in this way that the exponentially small Kondo scale from the strong-coupling regime emerges in qualitatively the same way in the spectral function, magnetic susceptibility and the specific heat. [ABSTRACT FROM AUTHOR]

We investigated temperature dependence of differential conductance G ( V ) in planar junctions consisting of Co-based Heusler alloy Co 2 TiSn and superconductor Pb. Ferromagnetic Co 2 TiSn was predicted to be half-metal by first-principles band calculations. The spin polarization P of Co 2 TiSn was deduced to be 60.0 % at 1.4 K by the Andreev reflection spectroscopy. The G ( V ) spectral shape was smeared gradually with increasing temperature and its structure was disappeared above the superconducting transition temperature T c . Theoretical model analysis revealed that the superconducting energy gap Δ was 1.06 meV at 1.4 K and the T c was 6.8 K , indicating that both values were suppressed from bulk values. However, the temperature dependent Δ ( T ) behavior was in good agreement with that of the Bardeen-Cooper-Schrieffer (BCS) theory. The experimental results exhibit that the superconductivity of Pb attached to half-metallic Co 2 TiSn was kept the conventional BCS mechanism characterized strong-coupling superconductors while its superconductivity was slightly suppressed by the superconducting proximity effect at the Co 2 TiSn/Pb interface. [ABSTRACT FROM AUTHOR]

We report the systematic investigation of structural properties, occupancy of density of states, nature of bonding and thermoelectric efficiency of half-Heusler ZrFeSi. The band structure analysis predicts the hybridization of Zr- d and Fe- d metal atoms resulting in occupation of density of states above the Fermi level (EF) while Fe- p and Si- p occupy the lower energy states below the EF. Thermoelectric transport coefficients are predicted using the Boltzmann transport theory under constant relaxation approximation, where Seebeck coefficient (S), total thermal conductivity and figure of merit are calculated. The negative value of total S as −14.02 μV/K predicts the material as n -type with thermoelectric figure of merit (zT) of 0.5 at 800 K. The lattice thermal conductivity decreases with increasing temperature with room temperature value of 4.18 W/mK and shows a significant reduction towards higher temperatures. In view of above elements, structural stability, high zT, ZrFeSi alloy have the capabilities to stimulate experimental verification as a promising materials for high temperature power generation and spintronic device fabrications. [ABSTRACT FROM AUTHOR]

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

We investigate the transport properties in a ferromagnetic silicene sheet in the presence of a velocity barrier, defining the region in which the Fermi velocity v F is tunable compared to other regions. It is shown that the valley and spin transports could be modulated by a pure velocity barrier. To achieve the high spin and valley polarization more efficiently, a local gate voltage is considered in the velocity barrier region, to induce a on-site potential difference between two sublattices of the silicene sheet. For the Fermi velocity inside the barrier smaller than the other regions, it is found that a velocity barrier induces a strong oscillation in the conductance and the valley and spin polarizations are strongly enhanced. In the opposite case, the valley and spin polarizations are suppressed by the velocity barrier. In particular, there exists a sharp transition of the polarizations by varying the Fermi velocity in this case, which has a potential application in the spin- and valley-polarized devices. [ABSTRACT FROM AUTHOR]

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

We investigated the effect of temperature on the electronic, elastic, and thermodynamic properties of Co -based full-Heusler Co 2 MnSi and Co 2 MnGe. The results show that the alloys are half-metallic ferromagnetic. The spin polarization is 97.90% for Co 2 MnSi , while for Co 2 MnGe is more than 85.3% below 1000 K. The study of elastic constants and their associated parameters predicted that the two alloys are mechanically stable in the temperature range of 0 – 1000 K. Both alloys are ductile, anisotropic, and characterized by ionic bonds. In addition, Co 2 MnGe is less hard than Co 2 MnSi , but the latter is more sensitive to temperature variations than Co 2 MnGe. The electronic and vibrational contributions to the thermodynamic properties were computed separately in the temperature range of 0 K to 1000 K. The high spin polarization and mechanical stability make these alloys more appropriate for spintronic applications. [ABSTRACT FROM AUTHOR]

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

The coupling between electric polarization and magnetization in single-phase bismuth ferrite BiFeO 3 (BFO) has a potential for low-power devices. To improve the switching ability of bismuth ferrite, the effect of lanthanum (La) at A-site, and manganese (Mn) at B-site as mono- and co-dopants on spin electronic properties, spin polarization, and spin magnetic properties of Bi 0.75 La 0.25 Fe 0.75 Mn 0.25 O 3 in cubic phase have been explored by using the first principles. An upsurge in the density of states is detected in the inclusion of Mn and La atoms, which modify the band gap in the spin-down state. Enhancement in the magnetic moment is observed on doping of Mn and La atoms in BFO as mono- and co-dopant due to the combined involvement of these impurities to terminate the cycloidal spin structure and activate the hidden spin. The switching properties such as linear Edelstein effect and spin polarization of co-doped BFO material enhanced to 1.612 × 10−9 m/V and 100% respectively whereas the high value of 2.161 × 10−11 (A/m2) spin current density, 3.600 × 10−2 (Sm−1) conductivity, and 9.200 × 10−11 (A/m2) charge current density have been detected in La-doped system. • First-principles calculations are carried out to tune conductivity, and magnetoelectric properties of pure and doped bismuth ferrite BiFeO3. • The calculations are performed in the Cambridge Serial Total Energy Package (CASTEP) code by using ultra-soft pseudopotential (USP) under GGA and LDA+U approach. • La pushes the BFO towards half-metallicity with interconversion of high spin and charge current densities. • Enhancement in magnetic moment (μ; B) is observed. • The nanoscale switching properties such as linear Edelstein effect and spin polarization of co-doped BFO material enhanced to 1.612×10-9 m/V and 100 % respectively whereas the high value of 2.161×10-11 (A/m2) spin current density, 3.600×10-2(Sm-1) conductivity, and 9.200×10-11(A/m2) charge current density have been detected in La-doped system. [ABSTRACT FROM AUTHOR]

We investigate the spin-polarized transport properties for magnetic junctions consisting of two ferromagnetic bilayer graphene (FBG) electrodes separated by a fourth-generation Thue-Morse bilayer graphene superlattice (TMBGS) or the corresponding periodic bilayer graphene superlattice (PBGS) under a uniform electric field. The spin conductance, spin polarization, and tunneling magnetoresistance (TMR) of the FBG/TMBGS/FBG junction are numerically calculated and compared with those of the FBG/PBGS/FBG junction. We find that the spin conductance can be greatly changed not only by the magnetization of the two FBG electrodes, but also by the exchange splitting energy. In the low energy range, the spin polarization and the TMR show drastic oscillations with increasing the Fermi energy. In the high energy range, the spin polarization and the TMR tend to be zero as the Fermi energy increases. Furthermore, compared to the FBG/PBGS/FBG junction, in the FBG/TMBGS/FBG junction, relatively large values of the TMR can be more easily obtained as the bias voltage increases. [ABSTRACT FROM AUTHOR]

Resorting to an external gate potential, we explore the spin–orbit coupling (SOC) in n-quantum-well structures with n subbands occupied, since n-well configuration is favorable to the flexible control of n-subband occupation for electrons in experiments. The charge transfer among the multiple local wells provides more possibilities of manipulation of the Rashba SOC. For all the systems we construct, from triple- to septuple-quantum-well structures, the SOC coefficient of the lowest subband is always much larger than those of the other subbands, which leads to greater spin splitting, conducive to desirable spin polarization. Furthermore, we demonstrate selective control of SOC via adjusting the gate, i.e., separately tuning the SOC coefficients of certain subbands while leaving those of the others unaffected by the gate. However, when more local wells are incorporated, the SOC coefficients of all subbands become weak gate-dependent in the case of n-subband occupation. All these findings are attributed to the charge redistribution among the subwells and the variation gradient of the potential energy along the growth direction of the quantum wells. Our results should provide new insight for experimental manipulation of the Rashba SOC in multiple-well structures. • Selective control of Rashba SOC of different subbands is realized in a wide gate potential range , facilitating the realization of persistent spin helix in quantum well semiconductors, which is crucial for spin-coherent transport. • Large spin splitting of the lowest subband is demonstrated, constructive to desirable spin polarization and detection. • When more local wells are incorporated, in the gate range where n subbands are kept occupied , Rashba SOC of all subbands become less gate-dependent. [ABSTRACT FROM AUTHOR]

Phosphorene has attracted great interest in spintronics. Here, the electronic structures of monolayer zigzag black phosphorene nanoribbons(ZBPNRs) are researched. We found that the magnetic ground state of ZBPNRs is dependent on nanoribbon widths. In addition, we examine the role of the surface adatoms including Li, Na, K, Mg, Ca and Al in modifying the electronic properties of ZBPNRs. Our calculations show that the adsorption systems with Li, Na and K are half-metals due to the localization of transferred charge. On the other hand, Mg, Ca and Al, which provide more valence electrons than Li, Na and K, result in a smaller net magnetic moment and prefer semiconductor or metal. Our findings propose a new approach without magnetic atoms, magnetic field and strong electric field to realize half-metal in phosphorene, which overcome the drawbacks of graphene/silicene with negligible band-gap as well as transition metal sulfide with low carrier mobility. [ABSTRACT FROM AUTHOR]

We theoretically study the single electron magnetotransport in GaAs and InGaAs vertically stacked bilayer nanowires. In considered geometry, the tilted magnetic field is always perpendicular to the main (transport) axis of the quantum wire and, therefore its transverse and vertical components allow separately for changing the magnitude of intralayer and interlayer subbands mixing. We study the changes introduced to energy dispersion relation E ( k ) by tilted magnetic field of strength up to several tesla and analyze their origins for symmetric as well as asymmetric confining potentials in the growth direction. Calculated energy dispersion relations are thereafter used to show that the value of a conductance of the bilayer nanowire may abruptly rise as well as fall by few conductance quanta when the Fermi energy in nanosystem is changed. It is also shown that such conductance oscillations, in conjunction with spin Zeeman effect, may give a moderately spin polarized current in the bilayer nanowire. [ABSTRACT FROM AUTHOR]

The metal–insulator like transition of the ferromagnetic (FM) state in Co 1 − x Fe x S 2 (0 ≤ x ≤ 0.7) with varying x is investigated using X-ray diffraction, Mössbauer spectroscopy, and magnetoresistance measurements. The linear decrease of unit cell parameter with x confirmed Fe substitution at the Co site. The room temperature Mössbauer study showed the absence of magnetic moment on Fe and both isomer shift and quadrupole splitting were found to vary linearly with x. The temperature-coefficient-of-resistivity (TCR) in the FM state became negative for x ≥ 0.15. For intermediate compositions i.e., x = 0.05 and 0.1, TCR changed from positive to negative (T ≤ T C) to positive with an increase in temperature. By studying the temperature-dependent and isothermal magnetoresistance data around the transition region, it was shown that resultant behavior could be arising due to changes in spin polarization over a broad temperature range. [ABSTRACT FROM AUTHOR]

We study the model of three-spin system by using Born-Markov master equation for density matrix. Three-spin system consists of a spin-1/2 quantum dot and two spin-1 magnetic particles arranged in triangular geometry and a quantum dot is also tunnel-coupled to ferromagnetic electrodes, respectively. In this case, we are interested in decoherence of entangled state of the system. Decoherence occurs due to tunneling of electrons through coupling to ferromagnetic electrodes. Therefore, an entangled state undergoes decoherence dependent on the spin polarization as well as magnetization orientations of electrodes. We have established master-equation formalism for the density matrix of three-spin system and calculated spin-spin correlation function between two magnetic particles corresponding to entangled state. The results show that with the increase of spin polarization, spin-spin correlation function for parallel configuration of electrodes' magnetizations decays more rapidly, while spin-spin correlation function for antiparallel configuration decays more slowly. [ABSTRACT FROM AUTHOR]

We report a theoretical study of the spin and valley dependent transport properties in a WSe 2 superlattice with external Rashba spin-orbit interaction (ERSOI). It is shown that the conductance with and without spin flip strongly depends on the ERSOI and has an oscillatory behavior with respect to ERSOI strength, thus WSe 2 superlattice can act as a spin-converter. Also, the magnitude of spin-dependent conductance can be efficiently controlled by potential barrier height and number of superlattice barriers. Results show that the valley and spin polarization depend on the number of superlattice barriers and exhibit an oscillatory evolution versus ERSOI strength and potential barrier height. These results clarify that a WSe 2 superlattice can be useful for the design of novel valleytronic and spintronic devices. [ABSTRACT FROM AUTHOR]

In this work, the (D = Mo, Ru)-doping effect on the electronic and magnetic properties of BaZrO 3 is investigated by means of the Korringa-Kohn-Rostoker (KKR) method in combination with the coherent potential approximation (CPA). It is shown that substituting Ba by different concentrations x of Mo and Ru impurities deals with ferromagnetic half-metallic compounds 100% spin polarization at the Fermi level. The same behavior is observed for Zr-doped configurations, except BaZr 1 −x Mo x O 3 for x > 14 which exhibits metallic character. The stability of the ferromagnetic order is attributed to double exchange mechanism. Doping induces a net moment of 1 μB for the Ba substitution cases (Ba 1 −x D x ZrO 3) and 3 μB for BaZr 1 −x D x O 3 conformers. Moreover, a high curie temperature, above ambient temperature is reached for the systems. Based on these results, we have designed half-metallic ferromagnetic compounds with high efficiency and great potential for spintronic applications. [ABSTRACT FROM AUTHOR]

We design a four InAs quantum dot system in which two leads are irradiated by terahertz light fields. The average current through the system is obtained by means of non-equilibrium Green's function theory. Typical photon-assisted tunneling is observed in the current energy spectrum. 100% polarization can be achieved by adjusting the intensity of Zeeman magnetic field or the amplitude of terahertz light field. As the frequency of terahertz light field is invariant, a zero current can be obtained by adjusting the amplitude of the terahertz light field, indicating an optically controlled quantum switch device. The spin polarization can be converted between 0 and 1 by tuning the energy level of quantum dots, suggesting a physical scheme of a polarization pulse device. Moreover, the system can be constructed as a terahertz detector due to the oscillation properties of spin polarization. The present work sheds lights onto the design of quantum computing and spin-dependent quantum devices. [ABSTRACT FROM AUTHOR]

The Formations, stabilities, evolutions of geometries, electronic states together with the spin polarization transitions involved with magnetic properties of the MnGa compound under c axis anisotropic stress are systematically studied within the framework of density functional theory analyzing method. The results show that the anisotropically geometric expansion can be induced under stress. There are five kinds of atomic distances within the compound, with larger distance values for Mn–Mn and Ga–Ga, and smaller distances for Mn–Ga. The induced atomic distance fluctuations are also anisotropic, corresponding to the anisotropic binding strength regulations. The compound under stress is more stable. The s orbital releases electrons, the p and the d orbitals accept electrons for Mn. The s orbital and the d orbital release electrons, the p orbital traps electrons for Ga. The Mn1 and Mn2, Ga1 and Ga2 have diversified configurations under stress. A transition of ionic state of Mn2 is observed. Electrons transfers occur between orbitals and species under stress. The MnGa has anisotropic conductor band structure. The effective mass of conduction band as well as shallow valence band are enhanced under stress. The electronic band experiences a transition from semimetal into metal. The s, p and d electrons form the conduction band and shallow valence band. The d electrons mainly form the deep valence band, too. The localization at −16.8eV of d electrons is weakened under stress. The Mnd electrons get less responsible for the spin state under stress. The Mn1 and Mn2 turn to exhibiting distinctively diverse profiles, the Ga1 and Ga2 turn to exhibiting the same profiles under stress. The Mn shows strong atomic magnetic moment than that of Ga. • Anisotropic structural distortions are induced by stress, corresponding to the anisotropic binding strength. • The Mn1 and Mn2, Ga1 and Ga2 have diversified configurations under stress. There is transition of ionic state of Mn2. • Electrons transfer between orbitals and species under stress. • The electronic band experiences a transition from semimetal into metal. [ABSTRACT FROM AUTHOR]

We have investigated TlGaS 2 single-layer and TlGaS 2 nanoribbons using density functional theory (DFT). Phonon dispersion curves calculated within the density functional perturbation theory indicate that the TlGaS 2 single-layer is dynamically stable. Starting from optimized TlGaS 2 single-layers, unterminated and terminated ribbon morphologies with varying edge Tl coverages were constructed. In order to account for the weak interaction between Tl and S atoms, van der Waals correction to DFT was employed. The electronic and magnetic structures of TlGaS 2 ribbons are modulated by the edge morphology. Dangling bond, non-bonding, and free-electron-like edge states are formed. The ribbons have metallic conduction channels stemming from parabolic bands crossing the Fermi level. The edge states appearing in the fundamental energy gap induce spin polarization at the edges. The TlGaS 2 nanoribbons provide two magnetic conduction channels along the Tl chains, and thus the nanoribbon acts as two magnetic nanowires. • It is possible to reach the single-layer limit in TlGaS 2 ultrathin. • The single-layer TlGaS 2 is semiconducting with a larger bandgap than bulk. • Parabolic bands appear in the electronic structure of TlGaS 2 nanoribbons due to the edge states. • The edge states in TlGaS 2 nanoribbons provide spin-polarized metallic conduction channels. [ABSTRACT FROM AUTHOR]

T-shape double quantum dot molecule A–B interference with the action of time-dependent external field is designed. Using the Keldysh non-equilibrium Green's function method, spin-dependent average current as a function of quantum dot energy is obtained. The magnitude and position of average current resonance peaks can be controlled by adjusting interdot coupling strength, frequency and amplitude of time-dependent electric field. The conversion between zero and non-zero value for average current can be realized under the condition with or without the action of time-dependent external field, respectively, which is the basis for the design of controlled quantum switch. Under the combined action of the external magnetic flux and Rashba spin–orbit coupling strength, the spin-polarized average current can be observed. Dc current–voltage characteristics are researched. [ABSTRACT FROM AUTHOR]

We design an A-B interferometer with a "single quantum dot atom" embedded in the upper arm and a "double quantum dot molecule" embedded in the lower arm. The transmission coefficient and average current characteristics are studied as the time-dependent external field is introduced. When the interdot coupling strength is weak, the change of Rashba spin orbit coupling strength has a strong influence on the spin transmission coefficient. When the interdot coupling strength and Rashba spin orbit coupling strength take appropriate values, the spin up and spin down transmission coefficients completely coincide, and a resonance band emerges at the Fermi level. The spin polarization can be close to +1 or −1 by adjusting the Zeeman magnetic field, the interdot coupling strength, and the gate voltage. In the presence of photon assistance, the spin polarization changes periodically in a certain proportion, so as to realize the spin-polarized transport with controllable time-dependent external field. These findings provide a theoretical basis for the spin polarized function of A-B interferometer. • The spin transmission coefficient produces Fano effect at the Fermi level. • The system can be used as a spin filter by adjusting the Zeeman magnetic field and the gate voltage. • When the time-dependent external field is introduced, the spin polarization changes quasi periodically. • The system can be used to realize the electrical components of spin current polarization transport unit. [ABSTRACT FROM AUTHOR]

High spin polarization of half-metallic ferromagnets is crucial for spintronic application. However, the appearance of defects will lead to the decrease of spin polarization. Coherent potential approximation within the full-potential local orbital minimum-basis method is applied to simulate the defect effects of MgN with zinc-blende structure. Our results reveal that the stability is reduced due to the formation of defects, while the majority-spin states across the Fermi level decrease the degree of spin polarization, only the defects at the vacant sites preserve the half metallicity of bulk MgN. In addition, the magnetic moments for N antisite defects obey nearly the Slater–Pauling rule within − 0.2 ≤ x ≤ 0 concentration due to their high spin polarization. Thus, our study may provide some valuable hints for the fabrication of magnetoelectronic devices with smaller energy losses by the tune of concentration of atomic impurities. [ABSTRACT FROM AUTHOR]

In this paper we study the formation of bound states in the continuum in a quantum dot molecule coupled to leads and their potential application in spintronics. Based on the combination of bound states in the continuum and Fano effect, we propose a new design of a spin-dependent polarizer. By lifting the spin degeneracy of the carriers in the quantum dots by means of a magnetic field the system can be used as a spin-polarized device. A detailed analysis of the spin-dependent conductance and spin polarization as a function of the applied magnetic field and gate voltages is carried out. [ABSTRACT FROM AUTHOR]

By using extended SSH Hamiltonian plus long-range electron correlation Hamiltonian model, we calculated charge injection and spin polarization in a ferromagnetic metal/polymer/ferromagnetic metal structure. We adjust relative chemical potential between the ferromagnetic materials and the polymer to control charge transfer. It is found that when spin orientations of two ferromagnetic materials are parallel to each other, spin-polarized single polaron can be formed in the polymer, but when the spin orientations of two ferromagnetic materials are antiparallel to each other, bipolaron is formed and that spin polarization is found to be zero inside the polymer. The influence of the long-range electronic correlation on these polarons in the polymer is discussed. [ABSTRACT FROM AUTHOR]

The robustness of the Dirac-like states in topological insulators depends on the preservation of the time-reversal symmetry. A magnetic impurity can locally break this symmetry and destroy the protected edge states. However, it is not clear how the influence of this symmetry breaking field depends on the distance between the edge structures (surface or interface) and the magnetic impurity. In this work we use the density functional theory to study the properties of the HgTe/CdTe (001) interface and the (001) HgTe surface in the presence of a Fe impurity. Our results show that for a Fe impurity in the HgTe/CdTe, the spin polarization in the edge states decreases due to the coupling between the magnetic moment of impurity and the magnetic moment of heterostructure, inducing an out-of-plane spin polarization at the interface or surface. • Effect of local magnetic fields on topological states. • Evaluation of the coupling between a magnetic impurity and topological states. • Robustness of topological states against a local magnetic field. [ABSTRACT FROM AUTHOR]