[en] The magnetic properties of one to four V monolayers (ML) on 5d transition metal W(0 0 1) substrate are investigated by using the all-electron full-potential linearized augmented plane wave method within the local spin density approximation. For 1 ML V on W(0 0 1), the surface V layer exhibits a somewhat large magnetic moment (1.35 μ_B) but smaller than that of V/Ag(0 0 1). The interface W layer for 1 V ML system shows a small but sizable induced magnetic moment (-0.14 μ_B) antiferromagnetically (AF) coupled to the V surface layer, which is considered to originate from strong sp hybridization between V overlayer and W substrate. For 2 ML V on W(0 0 1), the surface V layer shows a slightly reduced magnetic moment (1.05 μ_B) but nearly the same value as that of V on Ag(0 0 1) while the interface V layer has a much smaller one (-0.22 μ_B) and AF coupled to the V surface layer. We also found that the V overlayers with more than 3 ML on W(0 0 1) are nonmagnetic, which is justified from our calculations for 3 ML V/W(0 0 1) and 4 ML V/W(0 0 1) systems. The layer-projected spin-polarized density of states are discussed in relation to the magnetic properties of the V overlayers on W(0 0 1) substrate

[en] The electronic structure and magnetic properties of Fe₄N(0 0 1) with (Fe, N) and (Fe, Fe) surfaces have been investigated by using the full-potential linearized augmented plane wave method. From the investigation of the calculated magnetic moments, density of states, and charge densities, we conclude that the surface has very little effect on the magnetic properties of Fe(II) atoms as in inner layers in system with (Fe, N) surface, while the surface Fe(I) atoms are dominant for the magnetic properties of Fe(II) atoms in system with (Fe, Fe) surface. We have discussed several charge transfer models in relation to our calculations for the number of electrons in each muffin-tin sphere, but cannot definitely determine a model which is exactly consistent with our result

[en] The interaction of alkali metal adsorbates with transition metal surfaces has received much attention for practical and academic reasons. The interface magnetism of Fe in p(2x2) K/Fe(1 1 0) is investigated by using the all-electron full-potential linearized augmented plane wave (FLAPW) method within the local spin density approximation (LSDA). We found that the magnetism of interface Fe is suppressed by the interaction with adsorbed K: the magnetic moment of interface Fe atom (2.57 μ_B) is slightly smaller than that of clean Fe(1 1 0) surface (2.65 μ_B). The calculated work function (3.16 eV) for p(2x2) K on Fe(1 1 0) is smaller than that of Fe (4.31 eV) while larger than those of the experimental one (2.32 eV) for a perfect single K layer on Fe(1 1 0) and K (2.22 eV). Calculated density of states are presented and discussed in relation with magnetic properties of interface Fe

[en] We have performed first-principles electronic structures calculations for a Ni overlayer on Cu₃Au(0 0 1) substrate with Cu termination by using the all-electron full-potential linearized augmented plane wave method, with the generalized gradient approximation. Ni/Cu(0 0 1) system with the same lattice constant of Cu₃Au(0 0 1) has also been calculated for comparison. It is interesting that calculated magnetic moments of Ni on Cu₃Au(0 0 1) substrate depend on their sites. The magnetic moment of Ni on Cu site is calculated to be 0.62 μ_B, which is the same value as that of the Ni on Cu(0 0 1) substrate, while that of the Ni on Au site is reduced to 0.57 μ_B. The calculated layer-projected densities of states reveal that the difference in magnetic moments depends delicately on subsurface atoms and the subsurface atoms affect the detailed electronic structures near the Fermi level of Ni overlayers

[en] The effects of lattice strain on the electronic structures and the spin magnetic properties of CoFe in the CsCl (B2) structure were studied using first-principles electronic-structure calculations based on the density functional theory. The calculations in this study showed that the lattice stain induces significant changes in the peak positions of the majority-spin and the minority-spin densities of states: In the case of lattice expansion, band narrowing was observed while in the case of lattice compression, band broadening was observed. As a result, when the lattice strain of CoFe was increased to 4.7%, the minority-spin density of states at the Fermi energy decreased by 32% as compared to that of the unstrained CoFe. This suggests that lattice strain can play an important role in the functioning of spin electronic devices of CoFe.

[en] Ab-initio electronic-structure calculations have been performed to investigate the adsorption structures, the energetics, and the electronic structures of a Pt monolayer (ML) deposited on a MgO(001) surface. Our calculations for a 1-ML Pt/MgO(001) structure show that the Pt atoms highly prefer to bind on the oxygen sites of the MgO(001) surfaces. Also examined were the electronic properties of 1-ML Pt/MgO(001). Interestingly, the oxide-supported ultrathin 1-ML Pt film was predicted to be ferromagnetic with a magnetic moment of 0.89 Bohr magnetons. In addition, the origin of the unusual magnetism in 1-ML Pt/MgO(001) was discussed in comparison with calculations for a freestanding Pt monolayer.

[en] Possible 4d magnetism of a Rh monolayer in a Cu/Rh/Cu(001) system is investigated using the full-potential linearized augmented-plane-wave (FLAPW) energy band method based on the local-spin-density approximation (LSDA). We have calculated the total energy of the Cu/Rh/Cu(001) system and have found that the Rh monolayer is ferromagnetic (FM) with a tiny magnetic moment. However, the total energy difference between the ferromagnetic and the paramagnetic states is found to be very small, and thus which state can be realized at room temperature is uncertain. The calculated charge densities and layer-projected density of states (LDOS) are presented and discussed in relation to the magnetic properties

[en] We investigated the magnetism and half-metallicity for the superlattice of zinc-blende (CrTe)₁(VTe)₁(001) by calculating the electronic structures using the all-electron full-potential linearized augmented plane wave (FLAPW) method within the generalized gradient approximation (GGA). From the calculated atom-projected density of states (DOS) of the (CrTe)₁(VTe)₁(001) superlattice, we found that the minority spin states have band gaps of ∼2.3eV which is comparable to those of bulk CrTe and VTe in the zinc-blende structure. The lower and upper bounds of the band gaps for the superlattice are found to be in between those of bulk CrTe and VTe. The calculated magnetic moments for Cr and V atoms in the superlattice were about 3.7 and 2.5μ_B, which are similar to those of Cr atom in bulk CrTe and V atom in bulk VTe

[en] The resistivity, magnetic susceptibility, magnetization and specific heat under magnetic fields were measured on a Eu_0.7Na_0.3Fe₂As_1.4P_0.6 single crystal. A decrease in resistivity to zero, which shifted toward lower temperatures under a magnetic field, was observed at T_c ∼ 25 K due to a superconducting transition. The electrical and magnetic anisotropy was quite small. In low-field magnetization, helimagnetism appeared at T_HM ∼ 19 K, which changed to ferromagnetism in higher fields. Therefore, superconductivity coexists with helimagnetism in a low field but with ferromagnetism in a high field. The specific heat showed anomalies due to the helimagnetic and superconducting transitions as well as the temperature dependence caused by ferromagnetic spin waves in the low temperature regions. The Sommerfeld constant γ was extraordinarily large in the normal and superconducting states. The superconducting and magnetic transitions under magnetic fields with the H||ab-plane and H||c-axis configurations were summarized in a phase diagram.