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Using the first-principles calculations based on density functional theory (DFT) within the generalized gradient approximation (GGA), Ti2RuAl full-Heusler compound is studied. The electronic structure, magnetic, and optical properties of Ti2-based full Heusler compound Ti2RuAl are calculated and analyzed using the Wien2k package. The CuHg2Ti-type structure is found to be more favorable than the AlCu2Mn-type structure for this compound. The Ti2RuAl Heusler compound exhibits a ferrimagnetic half-metallic behavior with the total magnetic moment of 1 µB at the equilibrium lattice constant 6.24 Å. The total magnetic moment of Ti2RuAl is in agreement with the Slater-Pauling rule mtot = ztot–18 and hence has integral magnetic moments which is due to 100% spin polarization at Fermi energy. Ti2RuAl has an energy gap in the spin-down channel of 0.229 eV. This compound keeps a 100% of spin polarization for lattice constant change in the range of 5.8–6.5 Å. The Curie temperature of Ti2RuAl is estimated to be 451 K using the mean field approximation (MFA). In addition, optical properties like dielectric function, reflectivity, energy loss function, absorption coefficient, and optical conductivity are calculated. [ABSTRACT FROM AUTHOR]

The ab initio investigations of Mx (M = Y, Zr, Nb)–Sc1-x–Sn diluted ternary alloys were calculated for x = 0.25, 0.125, and 0.0625 ratios in GGA and GGA + mBJ methods. Half-metallic band gaps were observed in the spin-up electron states. Only the spin-up electrons of the Nb0.25Sc0.75Sn alloy cut the Fermi energy level and reduced the spin polarization amount to 75.24%. Band gap values were also obtained in both GGA and GGA + mBJ methods. When the GGA + mBJ method was used, an increase was observed in the half-metallic characters of the alloys. Therefore, all the alloys were obtained as true half-metallic ferromagnetic materials. Total magnetic moment values were obtained as 4.00 μB/f.u. in all ratios of Y–Sc–Sn alloys. Since Y and Sc are in the same period, this result is expected for half-metallic alloys. While the total magnetic moment was 3.00 μB/f.u. for the 0.25 ratio in the Zr–Sc–Sn alloy, it was obtained as 3.50 μB/f.u. and 3.75 μB/f.u. for the 0.125 and 0.0625 ratios, respectively. While the total magnetic moment of the Nb0.25Sc0.75Sn alloy was obtained as 1.923 μB/f.u., the magnetic moment values increased to 3.00 μB/f.u. and 3.50 μB/f.u., respectively, when the amount of Sc increased. In short, considering both their electronic and magnetic properties, Mx (M = Y, Zr, Nb)-Sc1-x-Sn ternary alloys are quite suitable for spintronic applications. [ABSTRACT FROM AUTHOR]

In this work, we have studied the structural, thermal, elastic and magnetoelectronic properties of FeNiMnZ (Z = Al, Si) Heuslers under pressure using the pseudo-potential plane wave method. The structural optimization was performed by considering three atomic arrangements in magnetic and non-magnetic states. It was found that FeNiMnZ Heuslers are chemically stable and crystallize in the ferromagnetic YI-type structure. At zero temperature (0 K) and zero pressure (0 GPa), the obtained lattice constant (a) and bulk modulus (B) are in good accordance with the literature. The determined elastic constants (Cij), Pugh's ratio (B/G), and universal elastic anisotropy index (AU) under pressure reveal that FeNiMnZ Heuslers are mechanically stable up to 76 GPa, behave in a ductile manner, and exhibit a notable elastic anisotropy, respectively. The band structure analysis shows that FeNiMnAl Heusler compound changes from perfect half-metallic to a metallic nature at 50.2 GPa, while FeNiMnSi Heusler compound keeps its metallicity throughout the considered pressure range. The spin polarization and total magnetic moment of FeNiMnAl (FeNiMnSi) material decrease under pressure varying from 50.2 to 88 GPa (from 0 to 80 GPa). Below 50.2 GPa, FeNiMnAl material exhibits 100% spin polarization and a total magnetic moment of 4μB, which makes it hopeful in spintronic applications. [ABSTRACT FROM AUTHOR]

We present a combined investigation of the electronic structure of bulk arc-melted full-Heusler Co 2 - x Fe 1 + x Si (x = 0, 0.5, 1) and CoFeSi alloys using density functional theory and ultrasoft X-ray emission spectroscopy. We perform first-principles calculations of the spin-polarized total and partial density of states for the Co and Fe 3d (s, p) as well as for the Si 3s (p, d) orbitals. It is demonstrated that only Co 2 FeSi alloy exhibits a half-metallic behavior. However, the inverse CoFe 2 Si alloy shows pseudogap and high spin polarization at the Fermi level. We carry out ultrasoft X-ray emission Si L 2 , 3 measurements, which provide the information about the local partial density of states of Si 3s and 3d orbitals in the valence band localized on Si atoms. We compare the measured spectra with our theoretical calculations and discuss them in terms of the contribution of s and d-electrons to the bonding. The Si and transition-metals sd and dd bonding formation is shown in the Co 2 - x Fe 1 + x Si and CoFeSi alloys. The high spin polarization values, along with the extremely high Curie temperature, make these compounds potential candidates for spintronic applications. [ABSTRACT FROM AUTHOR]

Since the charge transport has a sensitive property near the boundary, the GH shift and spin polarization are reexamined with a parallel double barrier magnetic nanostructure. It shows there exists a much stronger GH shift and spin polarization when the transmitted wave vector is much closer to zero by modulating the magnetic fields strength and incident energy. Furthermore, the influence on spin polarization is studied by changing the angle between two magnetic fields. It revealed that a stable spin polarization can be obtained by changing angle under some specific applied voltage and incident energies. Our results indicate a need for caution in boundary condition and tuning of angle. These interesting properties may provide good ideas to design and fabricate a spin beam splitters or filters. The influence of the symmetry breaking of magnetic fields on the spin polarization is studied by changing the angle between both magnetic fields. [ABSTRACT FROM AUTHOR]

The physical properties of Fe2CoAl (FCA) Heusler alloy are systematically investigated using the first-principles calculations within generalized gradient approximation (GGA) and GGA+U. The influence of atomic ordering with respect to the Wyckoff sites on the phase stability, magnetism and half metallicity in both the conventional L21 and XA phases of FCA is focused in this study. Various possible hypothetical structures viz., L21, XA-I, and XA-II are prepared by altering atomic occupancies at their Wyckoff sites. At first, we have determined the stable phase of FCA considering various non-magnetic (or paramagnetic), ferromagnetic (FM) and antiferromagnetic (AFM) configurations. Out of these, the ferromagnetic (FM) XA-I structure is found to be energetically most stable. The total magnetic moments per cell are not in agreement with the Slater-Pauling (SP) rule in any phase; therefore, the half-metallicity is not observed in any configurations. However, FM ordered XA-I type FCA shows 78% spin polarization at the Fermi Energy (EF). Interestingly, the results of XA-I type FCA are closely matched with the experimental results. [ABSTRACT FROM AUTHOR]

The electronic structure and spin polarization properties of transition-metal (TM) doped monolayer MoSeTe are studied by using the first-principles calculations based on density functional theory. The calculated results demonstrate that V, Mn, Fe, Co and Ni doped MoSeTe monolayer show spin polarization with large magnetic moments. There exist strong p-d hybridization between the doped TM atoms and MoSeTe, so new spin impurity states appear around the Fermi level after TM doping, which induces the spin polarization of the systems. The calculated density of states, spin density distributions as well as the charge transfer indicate that the spin polarization caused by Co dopant is the largest one. This work suggests that TM atom doped MoSeTe has considerable application prospects in the research field of electronics and spintronics. [ABSTRACT FROM AUTHOR]

Indirect exchange interaction between two magnetic external atoms, named by Ruderman-Kittle-Kasuya-Yosida (RKKY) interaction, has been presented in the staggered armchair graphene nanoribbon. We have studied RKKY interaction as a function of distance between localized moments. It has been shown that a magnetic ordering along the z-axis mediates an anisotropic interaction which corresponds to a XXZ model interaction between two magnetic moments. The static spin susceptibility components of armchair graphene nanoribbon have been calculated to find exchange interaction between arbitrary components of magnetic moments. We have exploited Green's function approach in order to calculate spin susceptibility components of electronic gas in nanoribbon structure in the context of tight binding model Hamiltonian. The effects of parameter and ribbon width on the dependence of exchange interaction on distance between moments are investigated. Our results show the spin polarization along perpendicular to the plane leads to anisotropic behavior for exchange interaction between the two magnetic moments. In other words the spatial behavior of RKKY interaction between longitudinal components of magnetic moments is different from that of transverse components. [ABSTRACT FROM AUTHOR]

We have studied spin-resolved correlations in the warm-dense homogeneous electron gas by determining the linear density and spin-density response functions, within the dynamical self-consistent mean-field theory of Singwi et al. The calculated spin-resolved pair-correlation function g ( r) is compared with the recent restricted path-integral Monte Carlo (RPIMC) simulations due to Brown et al. [Phys. Rev. Lett. 110, 146405 (2013)], while interaction energy E and exchange-correlation free energy F with the RPIMC and very recent ab initio quantum Monte Carlo (QMC) simulations by Dornheim et al. [Phys. Rev. Lett. 117, 156403 (2016)]. g ( r) is found to be in good agreement with the RPIMC data, while a mismatch is seen in g ( r) at small r where it becomes somewhat negative. As an interesting result, it is deduced that a non-monotonic T-dependence of g(0) is driven primarily by g (0). Our results of E and F exhibit an excellent agreement with the QMC study due to Dornheim et al., which deals with the finite-size correction quite accurately. We observe, however, a visible deviation of E from the RPIMC data for high densities (~8% at r = 1). Further, we have extended our study to the fully spin-polarized phase. Again, with the exception of high density region, we find a good agreement of E with the RPIMC data. This points to the need of settling the problem of finite-size correction in the spin-polarized phase also. Interestingly, we also find that the thermal effects tend to oppose spatial localization as well as spin polarization of electrons. [ABSTRACT FROM AUTHOR]

To investigate quantum nature of two dimensional electrons subject to high perpendicular magnetic fields, usually a planar electronic Fabry-Pérot interferometer is utilized. In this work, we investigate an interferometer defined on a curved heterostructure. In the presence of a magnetic field perpendicular to the cylindrical axis, the location and the properties of the edge channels depend on the radial component of the magnetic field. Considering a curved structure, we perform numerical and semi-analytical calculations to determine widths of the incompressible edge states. We observe that the edge states form a closed loop for certain magnetic field strengths yielding observation of conductance oscillations, which can be manipulated by changing the Azimuthal angle mechanically. In addition, we investigate the effect of spin polarization on the edge state distribution considering Zeeman splitting and obtained odd integer edge states. The proposed experiment would yield a novel method to clarify the ongoing debate on the origin of conductance oscillations, namely whether they stem from Aharonov-Bohm phase or charging effects. [ABSTRACT FROM AUTHOR]

In this paper experimentally measured optical properties of intermetallic ternary compounds DyRhSn and HoRhSn are reported together with the spin-polarized calculations of the electronic structure within DFT+U method, accounting for electronic correlation effects in the 4f shell of Dy and Ho. A number of spectral and electronic characteristics are determined. The performed calculations allow one to qualitatively interpret the energy dependencies of the interband optical conductivity extracted from experimental ellipsometry measurements. [ABSTRACT FROM AUTHOR]

While it has been recently demonstrated that, for quasi-two-dimensional electron gas (Q2DEG) with one filled subband, the dynamic exchange fx and Hartree fH kernels cancel each other in the low-density regime rs →∞ (by half and completely, for the spin-neutral and fully spin-polarized cases, respectively), here we analytically show that the same happens at arbitrary densities at short distances. This motivates us to study the confinement dependence of the excitations in Q2DEG. Our calculations unambiguously confirm that, at strong confinements, the time-dependent exact exchange excitation energies approach the single-particle Kohn-Sham ones for the spin-polarized case, while the same, but less pronounced, tendency is observed for spin-neutral Q2DEG. [ABSTRACT FROM AUTHOR]