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Ab initio calculations based on density functional theory with the PBEsol method were utilized to examine the influence of hydrogen passivation, vacancies, and dopants on the electronic and magnetic properties of zigzag MgO nanoribbons with a width of w = 6 (6Z-MgONR). Calculations suggested that the 6Z-MgONR–2H configuration, which lacked magnetism and exhibited metallic characteristics, was the most stable configuration. Herein, this configuration with intrinsic defects and impurities were deeply considered. Finds revealed that individual VMg and VO vacancies induced magnetic moments of 0.624 μB and 0 μB, respectively. The calculated formation energy indicated that the occurrence of a single VMg was energetically favored than a single VO. Moreover, the three oxygen atoms adjacent to vacancy displayed inconsistent spin polarization directions, resulting in smaller magnetic moments than bulk MgO. Upon the introduction of Li or N impurities, LiMg under O-rich conditions exhibited the lowest formation energy. This was accompanied by an increase in total magnetic moments to 1.435 μB, which was significantly higher in the case of Mg vacancy. The corresponding spin-resolved charge density clearly demonstrated that the spin polarization was strongly localized at the right edge passivation of H atoms, with a minor contribution from the O atoms closest to the right edge H atoms. The NO/6Z-MgONR–2H configuration also exhibited total magnetic moments of 1.872 μB, but it had a substantially higher defect formation energy compared to the LiMg/6Z-MgONR–2H system. [ABSTRACT FROM AUTHOR]

In this work, the electronic and magnetic features of the Sc2MnSi bulk, surfaces, and the interface with the semiconductor CdTe (111) were thoroughly researched using the first-principles calculations. The Sc2MnSi alloy with equilibrium lattice constant of 6.34 Å shows half-metallic (HM) property. This alloy exhibits an energy gap and a HM gap of 0.54 and 0.12 eV, respectively. The density of states results confirm the existence of the half-metallicity property for the Sc2MnSi component at SiSc(2)-(001), Sc(2)-, and Si-(111) surfaces while this property is not revealed at Sc(1)-, Mn-terminated (111), Sc(1)Mn-terminated (001), and Sc2MnSi (110) surfaces for the same component. In addition, in the case of Sc2MnSi/CdTe interface, it is noted that Cd-Si connection does not reveal the half-metallicity feature, while the Si-Te shape exhibits a 100% spin polarization, thus preserving the half-metallicity. Furthermore, the Si-Te shape is more stable than the others, according to the interfacial adhesion energy. [ABSTRACT FROM AUTHOR]

In our previous works [J. Phys. Chem. Solids 163 (2022) 110600], the CrLaCoAl alloy had been predicted to be half-metallic ferrimagnet with high Curie temperature, and it met the dynamic, mechanical and thermal stabilities. Furthermore, a smaller convex hull indicated that it was likely to be prepared in experiment. However, the half-metallicity of CrLaCoAl alloy is possible to be destroyed by defect. Therefore, it is necessary to study the stability, electronic and magnetic properties of defective CrLaCoAl. Results show that the formation energies of the Cr–La, Co–Al swap and Al(Cr), Co(La) antisite are negative, indicating that they are likely to be formed in the process of crystal growth. Among them, the formation energy of the Al(Cr) antisite is the lowest in defects, and the spin polarization is as high as 93.72%. In addition, the spin polarization of all antisites is over 60% except for the Cr(Al), La(Cr) and La(Al) antisite. High spin polarization in defect is favorable in spintronic application. [ABSTRACT FROM AUTHOR]

In this paper, we perform first-principles calculations of substituting Cobalt impurity into Indium Arsenide (InAs) graphene-like, and investigate the electronic, magnetic and optical properties of the resulting compound compared to the pure InAs graphene-like. The calculations are executed using the full-potential augmented plane wave method in the framework of the density-functional theory using the computational Wien2k. Looking into the band structure and density of states diagrams in the electronic discussion, it is found that the energy gap is reduced with doping Cobalt into InAs graphene-like. Moreover, in magnetic analysis, we conclude that by substituting Indium atoms with Cobalt, the InAs nano-sheets are transformed from non-magnetic semiconductors to semi-metals with a magnetic moment of about 4µB due to a strong spin–orbit effect between the electrons and the nuclei of Co atoms. This compound reaches a 100% spin polarization and turns to a half-metal which can have lots of applications in spintronics industry. [ABSTRACT FROM AUTHOR]

In this manuscript, we investigate the physical properties such as the magnetic and the electronic properties of the Co-based equiatomic quaternary Heusler alloy CoYCrZ (Z = Si and Ge). These investigations have been performed by employing the Quantum Espresso code in the framework of density functional theory (DFT). The generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof (PBE) is used for all these calculations. The band structures, and density of states calculations, show that all these materials CoYCrZ (Z = Si and Ge) exhibit a half-metallic (HM) behavior only for the structure type II. Moreover, this structure type II is found to be the most stable configuration for all these alloys. On the other hand, it has been found that the Slater–Pauling is well described for the compound CoYCrGe, only for the configuration type II. In particular, the equiatomic quaternary Heusler alloys CoYCrSi and CoYCrGe are found to be half-metallic for the structure type II. This is due to the fact that they have 100% spin polarization SP. Also, the existence of complete SP in the studied alloys is the reason for which these materials are useful for spintronic device applications. [ABSTRACT FROM AUTHOR]

We report a theoretical study about the spin-dependent electron transport through a two-arm mesoscopic circuit in which two protein-like single-helical molecules connect serially with two normal metallic leads, respectively. Based on an effective-model Hamiltonian, the spin polarization is evaluated using the Landauer-Büttiker formula. Our results reveal that in comparison with the single-arm case, the spin-polarization efficiency can be enhanced in this system, by adjusting the length ratio of two molecules and the molecule-lead coupling manner. Besides, when local magnetic flux is introduced, the Aharonov-Bohm effect makes a nontrivial contribution to the spin polarization. These findings can be helpful for building the helical-molecule-based spin filters. [ABSTRACT FROM AUTHOR]

The electron-doped manganite CaNdMnO has been investigated through magnetic and electrical transport studies. It shows insulating behavior down to the lowest temperature (5 K) measurement even on application of high magnetic field (up to 15 T) indicating a robust insulating behavior. Small polaron hopping and variable range hopping conduction have been observed at high- and low-temperature region, respectively. High- T conductivity of the sample follows non-adiabatic hopping conduction mechanism. Magnetic field-dependent resistivity has been thoroughly examined in terms of a phenomenological model taking into account the spin-polarized tunneling (SPT) of the conduction electrons. In order to explore the nature of the temperature-dependent magnetoresistance (MR), we have separated the contribution related to SPT and spin fluctuation basing on the model. Scaled isothermal MR data collapse into two curves separating the charge order temperature ( T), which indicates the existence of general formalism of MR and also suggests temperature-independent behavior of the reduced MR. [ABSTRACT FROM AUTHOR]

This paper reports that the planar Hall effect in NiFe/Cu/IrMn multilayers was strongly influenced by the Cu spacer thickness ( t), which was due to the variation of interfacial roughness. With t increasing, a peculiar change of planar Hall voltage was observed. The reason for the voltage behaviors was that the interfacial roughness influenced the spin-asymmetry of spin-polarized electrons in ferromagnetic metals. The diffuse scattering to the electrons turned to specular scattering when the interface became flat, leading to the variation of resistivity change (Δ ρ). As the increase in t, the extremum field was reduced because of the weaken exchange coupling between NiFe and IrMn layers. [ABSTRACT FROM AUTHOR]

A carbon nanotube (CNT)/zigzag graphene nanoribbons (ZGNRs) junctions has been proposed and investigated by first-principles calculations. The results show that large spin polarization of currents would be achieved when only one edge of ZGNR is coupled to the other lead. By virtue of spatial separation of edge state in two spin channel, one of those channels is opened at certain energy range and gives rise to spin-polarized currents under a low bias. This feature is stable whenever the ZGNR lead is under the antiferromagnetic ground states or is under the ferromagnetic states. Our findings indicate that this approach is simple and efficient for spintronics design. [ABSTRACT FROM AUTHOR]

In this work, we have investigated the structural, electronic and magnetic properties of In1−xCrxSb alloys in zinc blende at concentrations x = 0.125, 0.25, 0.50, 0.75, 0.875 and 1. We have performed our calculations by the use of first-principle methods based on spin-polarized density functional theory, where the electronic exchange–correlation potential is treated by the generalized gradient approximation GGA-WC and the improved TB-mBJ approach. The calculated structural parameters of InSb are in good agreement with the available theoretical and experimental data. The ternary In1−xCrxSb alloys show half-metallic ferromagnetic behavior with a spin polarization of 100% at the Fermi level. The total magnetic moments are 3 μB for all compounds and the interaction is antiferromagnetic between Cr–Sb and Sb–In sites. These materials are half-metallic ferromagnets, and they can be potential candidates for spintronic applications. [ABSTRACT FROM AUTHOR]

Previous calculations indicate that the CoVTe half-Heusler alloy appears half-metallic (HM) with spin polarization equal to 100%. We predict the spin polarisation and related alloy properties for the CoVTe (001), (111), and (110) surfaces and interface with a BeTe semiconductor. All the calculations were based on the generalized gradient approximation (GGA) with the Clb structure, using a first-principles investigation. We find a weak relaxation with (001) terminations, meaning the two terminations are stable and have stronger relaxations with the V (111) surface. The (001) V–Te surface has half-metallicity (HM) preserved with the HM energy gap of 0.22 eV and full spin polarisation, so the surface is useful for applications in the field of spintronics when using thin films, while other surfaces showed a high spin polarisation with values of 85–96%. For The CoVTe/BeTe interface demonstrates a weak relaxation for both structures. For VTe–Te*, the HM is destroyed and the minority spin is close to the Fermi level, with a higher spin polarization equal to 93%. The VTe–Be configuration retains HM, suggesting it is a good candidate for spintronic applications. The values of the magnetic moment for the surface and interface are calculated because these values may change when used as a thin film. [ABSTRACT FROM AUTHOR]

Monte Carlo method is applied to the study of relaxation of excited electron-hole (e-h) pairs in graphene. The presence of background of spin-polarized electrons, with high density imposing degeneracy conditions, is assumed. To such system, a number of e-h pairs with spin polarization parallel or antiparallel to the background is injected. Two stages of relaxation: thermalization and cooling are clearly distinguished when average particles energy ⟨E⟩ and its standard deviation σE are examined. At the very beginning of thermalization phase, holes loose energy to electrons, and after this process is substantially completed, particle distributions reorganize to take a Fermi-Dirac shape. To describe the evolution of ⟨E⟩ and σE during thermalization, we define characteristic times τth and values at the end of thermalization Eth and σth. The dependence of these parameters on various conditions, such as temperature and background density, is presented. It is shown that among the considered parameters, only the standard deviation of electrons energy allows to distinguish between different cases of relative spin polarizations of background and excited electrons. [ABSTRACT FROM AUTHOR]