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The magnetic properties of Co-doped CdS has been investigated by ab initio calculations using the GGA + U approximation. The study reveals the ferromagnetic ordering of Co-doped CdS at lower concentrations of Co, whereas, at higher concentrations, the antiferromagnetic interactions dominate. The electronic structures reveal the half metallic character signifying 100% spin polarization. Significant hybridization between d states of Co and p states of S is observed in the density of states indicates the Co-induced ferromagnetism in CdS. The lower formation energy promises superior stability and shows that Co-doped CdS can be easily fabricated experimentally. [ABSTRACT FROM AUTHOR]

Materials with multifunctional properties are currently being studied for countless technological applications. In the present work, an experimental and theoretical study of the iron-chromite spinel FeCr2O4 produced by the solid-state reaction technique is reported. Structural analysis from x-ray diffraction experiments revealed the crystallization of the material into a cubic structure and morphological and compositional studies showed the granular character, with nanometric and micrometric dimensions whose compositions are as expected from its chemical stoichiometry. Optical characterization reveals semiconducting behavior with bandgap 1.52 eV and the magnetic response shows weak ferromagnetic character at room temperature. The density of electronic states in the ground state evidences characteristic semiconducting for one spin polarization and conducting for the other close to the Fermi level, which is compatible with a half-metallic behavior with magnetic moment of 2.0 µB per unit cell. [ABSTRACT FROM AUTHOR]

The new Ba1 − xTixS compounds based on the titanium (Ti)-doped BaS at various concentrations x = 0.25, 0.5, and 0.75 were characterized using the first-principle concepts of density functional theory. We investigated the doping effect of titanium on the structural and electronic properties, induced ferromagnetism, half-metallicity, and exchange splittings in Ba1 − xTixS materials. The origin of ferromagnetism in the Ba1−xTixS compounds is due to the localized partially occupied 3d (Ti) states related to the double exchange mechanism. The electronic structures of Ba1 − xTixS at concentrations x = 0.25 and 0.5 show half-metallic ferromagnetic character with spin polarization of 100%. For the concentration x = 0.75, the Ba0.25Ti0.75S compound exhibits a metallic nature for two spins channels due to widening 3d (Ti) states in the gap. Therefore, Ba1 − xTixS at concentrations x = 0.25 and 0.5 seems to be a candidate for spintronics. [ABSTRACT FROM AUTHOR]

Ab initio calculations based on density functional theory have been used to comparatively investigate the electronic and magnetic properties of two non-magnetic ions (Cu, K)-doped magnesium sulfide. The results obtained indicate that the ferromagnetic phase is always energetically favorable than the paramagnetic one. It is also found that these ternary alloys are half-metallic ferromagnets with a total magnetic moment of 1.00 μB per supercell. The ferromagnetism is induced by hybridization between Cu 3d and its nearest neighboring S 3p in Cu-doped MgS, while it originates in the spin polarization of the p shell of anions S in K-doped MgS. Our results make these compounds attractive materials for possible spintronics devices. [ABSTRACT FROM AUTHOR]

The pristine graphene described with massless Dirac fermion could bear topological insulator state and ferromagnetism via the band structure engineering with various adatoms and proximity effects from heterostructures. In particular, topological Anderson insulator state was theoretically predicted in tight-binding honeycomb lattice with Anderson disorder term. Here, we introduced physi-absorbed Fe-clusters/adatoms on graphene to impose exchange interaction and random lattice disorder, and we observed Anderson insulator state accompanying with Kondo effect and field-induced conducting state upon applying the magnetic field at around a charge neutral point. Furthermore, the emergence of the double peak of resistivity at ν = 0 state indicates spin-splitted edge state with high effective exchange field (>70 T). These phenomena suggest the appearance of topological Anderson insulator state triggered by the induced exchange field and disorder. [ABSTRACT FROM AUTHOR]

In ferromagnetic trilayers, a spin-orbit-induced spin current can have a spin polarization of which direction is deviated from that for the spin Hall effect. Recently, magnetization switching in ferromagnetic trilayers has been proposed and confirmed by the experiments. In this work, we theoretically and numerically investigate the switching current required for perpendicular magnetization switching in ferromagnetic trilayers. We confirm that the tilted spin polarization enables field-free deterministic switching at a lower current than conventional spin-orbit torque or spin-transfer torque switching, offering a possibility for high-density and low-power spin-orbit torque devices. Moreover, we provide analytical expressions of the switching current for an arbitrary spin polarization direction, which will be useful to design spin-orbit torque devices and to interpret spin-orbit torque switching experiments. [ABSTRACT FROM AUTHOR]

The first principles calculations are carried out to understand the half metallic and ferromagnetic properties of Fe2−xCoxTiSi (x = 0, 0.5, 1, 1.5, 2) full Heusler alloys. The stable structure is predicted as L21 structure (Cu2MnAl phase). The lattice constant value of Fe2−xCoxTiSi Heusler compounds increases as the value of x increases. These alloys exhibit half metallic ferromagnetism (except Fe2TiSi) with small spin flip gap at the minority spin state. At high pressure, semiconductor to metallic phase transition is observed in Fe2TiSi while half metallic to metallic phase transition is observed in Fe1.5Co0.5TiSi, Fe1.0 Co1.0TiSi, Fe0.5Co1.5TiSi and Co2TiSi. The spin polarization of these compounds (except Fe2TiSi) is 100%. Hence, these compounds are suitable for spin injection devices in spintronics. [ABSTRACT FROM AUTHOR]

We analyzed the electronic and magnetic properties of new Heusler alloys Zr2NiZ (Z = Ga, In, B) with Hg2CuTi type structures based on first principles calculations. All compounds exhibit a stable half-metallic properties with band gaps in the spin-minority state 0.48 eV, 0.54 eV, and 0.62 eV, for Zr2NiZ (Z = Ga, In, B), respectively, with spin polarization equal to 100%. The calculated magnetic moment of these compounds was found to equal 3 μB per formula unit values, which all follow the Slater-Pauling rule (SP) of Mt = Zt − 18. The Zr2NiZ (Z = Ga, In, B) compounds showed half-metallic properties with a total spin polarization equal to 100% over a wide range of values of the lattice constant, and this makes these inverse Heusler alloys of maximum benefit in a wide implementations of spintronic systems. [ABSTRACT FROM AUTHOR]

In this study, structural, electronic and magnetic properties of non-transition metal-based binary compounds X Bi (X = Ba, Sr and Ca) in five different phases: rock salt, NiAs, wurtzite, zinc blende and CsCl, are investigated in order to find new sp magnetic materials used for real spintronic and other related applications. The calculations are performed by a developed full-potential augmented plane wave plus local orbitals (FP-L/APW + lo) method within the spin density functional theory. As exchange-correlation potential, we used the generalized gradient approximation of Perdew, Burke, and Ernzerhof (GGA-PBE) and the modified Becke-Johnson potential mBJ-GGA-PBE form. It is found that the magnetic moment in these compounds is mainly contributed by the spin-polarized p orbitals of Bi atoms. The WZ XBi are true half-metallic ferromagnet with opposite spin direction at Fermi energy having a magnetic moment of 2.00 μ B per formula unit. [ABSTRACT FROM AUTHOR]

First-principle calculations are employed by means of an all-electron full-potential linearized augmented plane wave to investigate the electronic structure and magnetic properties of AlP, AlAs, GaP, GaAs, InP, and InAs-based dilute magnetic semiconductors (DMS) with Sr impurities. It is shown that, in all the cases the ferromagnetic phase is energetically favored with respect to the paramagnetic one. In addition, these alloys are found to be half-metallic ferromagnets with a net total magnetic moment of 1.00 μ when they assume the zinc-blende structure at the equilibrium lattice constant. Ferromagnetism is induced by the spin polarization of the p shells of anions; the magnetic moment mainly comes from anion atoms surrounding the dopant atom, which is different from conventional DMS. These theoretical results make these materials interesting candidates for spin injection in spintronic devices. [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic, and optical properties of Fe-doped and Co-doped zinc-blende (ZB) CdSe compounds were calculated and discussed in detail. The Fe-doped CdSe and Co-doped CdSe are found half-metallic ferromagnet with 100 % carrier spin polarization at the Fermi level. The net magnetic moment of 4 μ and 3 μ are found per supercell, respectively. The estimated Curie temperature of Fe-doped CdSe and Co-doped CdSe are predicted to be 344 and 210 K, one of which is higher than room temperature. The dielectric functions and the absorption coefficients are studied from the ground electronic states. The impurity states of Fe- and Co-dopants induced strong absorption in the UV-light range and visible region. Overall, Fe-doped CdSe and Co-doped CdSe in the ZB phase show half-metallic ferromagnetic nature and are expected to be potential materials for spintronic devices and optical devices. [ABSTRACT FROM AUTHOR]

The objective of this work is to predict the structural, electronic and magnetic properties of Mg Cr S ( x = 0, 0.25, 0.50, 0.75 and 1) compound in the zinc blende ferromagnetic phase using the first principal approach. The structural properties are performed using the generalized gradient approximation developed by Perdew-Burk-Ernzerhof (PBE-GGA). However, the electronic and magnetic properties have been performed using the modified Becke-Johnson potential combined with the LDA correlation (mBJLDA) which provides better description of electronic properties than PBE-GGA. The results show that this compound exhibits a half-metallic ferromagnetic character with 100 % spin polarization at the Fermi level. For all Cr concentrations (0.25, 0.50, 0.75 and 1), the total magnetic momentum is equal to 4 μ , and there is a small local magnetic moment on the Mg and S sites. Furthermore the local magnetic moments of Cr atom reduce from their free space charge value. [ABSTRACT FROM AUTHOR]

The structural, electronic, and magnetic properties of new quaternary RhFeTiZ (Z = Al, Si) Heusler alloys were investigated, using the first-principle full-potential linearized-augmented plane wave (FP-LAPW) method with both generalized gradient approximation with Hubbard term U (GGA + U) and GGA + U plus modified Beck-Johnson (GGA + U + mBJ) exchange potentials. The RhFeTiZ (Z = Al, Si) compounds are stable in the ferromagnetic type I structure. The electronic and magnetic properties of RhFeTiZ (Z = Al, Si) compounds were calculated with GGA + U and improved with GGA + U + mBJ potential in the stable type I structure. We found that RhFeTiAl is a conventional semiconductor for both GGA + U and GGA + U + mBJ potential, whereas the RhFeTiSi is a nearly half-metallic for GGA + U and exhibits a half-metallic ferromagnetic behavior with spin polarization of 100 % for GGA + U + mBJ potential. The total magnetic moments are 0 and 1 μ for RhFeTiAl and RhFeTiSi, respectively, which are in agreement with the Slater-Pauling rule. Therefore, the RhFeTiSi seems to be a potential candidate for spintronic applications. [ABSTRACT FROM AUTHOR]

We have calculated the electronic structure and magnetic properties of the alloys GaCrAs compound, using the full-potential linearized augmented plane-wave (FLAPW) method based on density functional theory (DFT). Spin-polarized calculations show that the GaCr compound is half-metallic ferromagnetic with a magnetic moment of 3.00 μ at the equilibrium lattice constants. The half-metallic character is confirmed by the integral total magnetic moment of 3.00 μ per unit cell. The results presented here are theoretical predictions that can be used in magnetic applications. [ABSTRACT FROM AUTHOR]

Within the framework of density functional theory, the electronic structure and magnetic properties have been studied for the LiXCl (X = V, Mn, Co and Fe) Suzuki-type compounds. Features such as the lattice constant and the bulk modulus and its pressure derivative are reported. The LiXCl (X = V, Mn, Co and Fe) Suzuki-type compounds show half-metallic ferromagnetism with total magnetic moments ( M ) of 3, 5, 3, and 4 μ per formula unit, respectively. The half metallicity is originated by the hybridization of TM-d states with Cl-p states. The analysis of charge density contours leads us to conclude that the bonding character in these compounds is a mixture between covalent and ionic natures. The half-metallic nature and complete 100 % spin polarization show that the new compounds have a potential application in spintronic devices. [ABSTRACT FROM AUTHOR]

We have investigated the magnetic stability and electronic properties of the compound CrGeC using the framework of an all-electron full-potential linearized augmented-plane wave (FP-LAPW) method within the generalized gradient (GGA) and + U corrected (GGA + U) approximations. An antiferromagnetic spin ordering of Cr atoms is shown to be the grand state for this compound. Based on its electronic band structures and density of state (DOS), CrGeC has a metallic character, and from the analysis of the site and momentum projected densities, it is deduced that the bonding is achieved through hybridization of Cr-3d with C-2p states and Cr-3d with Ge-3p states. It is also pointed out that the Cr-C bonding is more covalent than that of Cr-Ge. In the ferromagnetic (FM) phase, the spin-polarized calculation indicates that the total magnetic moment of CrGeC increases from 0.016 to 3.7 μ. Finally, we conclude that the treatment of the correlated electrons is important for the correct description of this material. [ABSTRACT FROM AUTHOR]

The electronic structures of LaNiO, where additional interstitial oxygens are forming stripes along (1,1,0), are presented. Spin-polarized calculations show that ferromagnetism on Ni sites is reduced near the stripes and enhanced far from the stripes. Totally, the magnetic moment becomes reduced because of interstitial oxygens. It is suggested that the oxygen interstitial concentration in oxygen-rich domains in nickelates suppress magnetism and give multiband metallic domains. [ABSTRACT FROM AUTHOR]

We have investigated point contacts between ferromagnetic Fe and different BCS-type superconductors using Andreev reflection spectroscopy. With the standard BTK-type analysis, the extracted spin polarization of Fe does not depend on the superconductor and agrees well with literature data. However, the characteristics of the Andreev reflection spectra vary with the superconductor. While most of the contacts with the strong superconductors Nb and Ta appear to be barely affected by the presence of Fe, the contacts with weaker superconductors Sn and Al have a reduced critical temperature $$T_\mathrm{c}$$ and occasionally a second superconducting transition at still lower temperature, and contacts with the weakest superconductor Zn have strongly reduced superconducting anomalies. We propose that this variation is related to the magnetic field generated by the ferromagnetic electrode, which can also affect the extracted spin polarization. [ABSTRACT FROM AUTHOR]

In this study, we have explored the structural, electronic, and magnetic properties of V-doped zincblende MgSe and MgTe compounds using density functional calculations. The Wu-Cohen generalized gradient approximation is used for optimizing the structural properties, while the modified Becke and Johnson local (spin) density approximation functional has been employed to compute the electronic and magnetic properties. The spin dependent band structures, electronic density of state, and magnetic moments calculated for V-doped MgSe and MgTe semiconductors exhibit occurrence of 100 % spin polarization at the Fermi level which confirms stable half-metallic ferromagnetism in these materials. The spin-down gaps and the half-metallic gaps are analyzed in terms of V- 3d and Se-4 p (Te-5 p) hybridization, where it is observed that the V- 3dstates play a key role in generating spin polarization and the magnetic moment in these compounds. The exchange constants N αand N β have been calculated to demonstrate the effects resulting from exchange splitting process. Furthermore, spin-polarized charge density calculation is presented for elucidating the bonding nature, while pressure dependence of total magnetic moment for three concentrations of V-doped MgSe and MgTe are also discussed. [ABSTRACT FROM AUTHOR]

The development of materials that are non-magnetic in the bulk but exhibit two-dimensional (2D) magnetism at the surface is at the core of spintronics applications. Here, we present the valence-fluctuating material EuIr2Si2, where in contrast to its non-magnetic bulk, the Si-terminated surface reveals controllable 2D ferromagnetism. Close to the surface the Eu ions prefer a magnetic divalent configuration and their large 4f moments order below 48 K. The emerging exchange interaction modifies the spin polarization of the 2D surface electrons originally induced by the strong Rashba effect. The temperature-dependent mixed valence of the bulk allows to tune the energy and momentum size of the projected band gaps to which the 2D electrons are confined. This gives an additional degree of freedom to handle spin-polarized electrons at the surface. Our findings disclose valence-fluctuating rare-earth based materials as a very promising basis for the development of systems with controllable 2D magnetic properties which is of interest both for fundamental science and applications. [ABSTRACT FROM AUTHOR]

Spin-transfer torque nano-oscillators (STNO) are important candidates for several applications based on ultra-tunable microwave generation and detection. The microwave dynamics in these STNOs are induced by spin currents that are typically generated either by spin polarization in an adjacent ferromagnetic layer or through the spin Hall effect. In this paper, a 3-terminal STNO based on a magnetic tunnel junction is excited by both of these spin injection mechanisms. The combination of these two mechanisms excites the free layer into dynamic regimes beyond what can be achieved by each excitation mechanism individually, resulting in enhanced output powers, a key figures of merit for device performance. The system response can be coherently quantified as a function of the total injected spin current density. The experimental data shows an excellent consistency with this simple model and a critical spin current density of 4.52 ± 0.18 × 109ħ/2 e−1 Am−2. Spin torque nano-oscillators are important candidates for several device applications. The authors demonstrate that the combination of two excitation methods, spin-polarised tunnelling current and pure spin Hall current, allows them to achieve greater injected spin current densities and power output than by each individual mechanism. [ABSTRACT FROM AUTHOR]