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Abstract: The magnetic and electronic properties of both linear and zigzag bimetallic chains of Fe–Ir, Co–Ir and Ni–Ir have been calculated based on density functional theory and using the generalized gradient approximation. It is found that all considered zigzag chains form a twisted two-legged ladder, look like a corner-sharing triangle ribbon, and have a lower total energy than the corresponding linear chains. All the Fe–Ir, Co–Ir and Ni–Ir linear and zigzag chains have stable or metastable ferromagnetic (FM) states. The bond lengths in bimetallic Fe–Ir, Co–Ir and Ni–Ir at ferromagnetic state are larger than those in the corresponding structures at nonmagnetic state. Interestingly, the Ni–Ir zigzag nanowire has two energy minimum states, both ferromagnetic and nonmagnetic (NM), indicating a possible stable condition for mechanically controllable break-junction experiments. [Copyright &y& Elsevier]

Abstract: The electronic structures of four polycrystalline borocarbide superconductors Y1-xRxPd2B2C (R = Gd, Dy, Ho, and Er) were studied by photoabsorption spectroscopy and theoretical calculation. The Pd and rare-earth L3-edge X-ray absorption near edge spectra (XANES) are compared with the calculated XANES spectra for these intermetallic compounds. The decrease of the superconducting transition temperatures with addition of rare-earth dopant in these compounds is not due to a decrease of the total density of states at the Fermi energy. [Copyright &y& Elsevier]

The electronic structure, mechanical and magnetic properties of Ni3Al, Ni3Ga and Ni3In have been studied by spin-density functional theory with generalized gradient approximation and also by X-ray absorption near-edge spectra (XANES) at the Ni, Ga K edges. The calculated lattice constants and bulk modulii are in good agreement with experiments. All three compounds have a similar calculated density of states (DOS) spectrum and are predicted to be a weak ferromagnet. The measured Ni(Ga) K-edge XANES are well explained by the theoretical XANES and unoccupied Ni(Ga)-p DOS, suggesting that XANES is a useful probe of the electronic structure of the intermetallics. [Copyright &y& Elsevier]

Abstract: Based on the density functional theory calculations, the structural optimization, magnetic stable phase, and electronic structure of the double perovskites Sr2ZnBO6 (B=Tc, Re, Ru, Os, Co, Pd, and Au) were investigated with full structural optimization by using the generalized gradient approximation (GGA) and by adding the correlation effect (GGA+U). The results indicate that all compounds can be stable half-metallic ferromagnetic materials in the GGA(+U) scheme with a spin splitting e g band of the B ion, which causes half-metallicity at the Fermi level except Sr2ZnCoO6 becomes a conductor in GGA+U scheme. We suggest that the double exchange interaction dominates the half metallicity and magnetism in these materials. [Copyright &y& Elsevier]

Abstract: Electronic structures of transition metal pnictides double perovskite La2NiMO6 (M=Mn, Tc, Re, Ti, Zr, and Hf) were shown as ferromagnetic (FM) insulators based on density functional calculation results. The FM state observed in La2NiMO6 (M=Mn, Tc, and Re) was most likely a mixture of high spin (HS) and low spin (LS) states; the electrons were transferred from the filled LS Ni e g states to the half-filled HS Mn (Tc). On the other hand, the FM state in La2NiMO6 (M=Ti, Zr, and Hf) was caused by the electron transfer from the half-filled LS Ti (Zr and Hf) e g orbital of HS Ni to the empty e g orbital of LS Ti (Zr and Hf). The FM insulating state of La2NiMO6 (M=Mn. Tc, Ti, Zr, and Hf) remained the same, whereas it changed from metal to insulator for La2NiReO6 based on the generalized gradient approximation+U calculation. [Copyright &y& Elsevier]

Abstract: We investigated the possible candidates of half-metal (HM) material in double perovskites structure Sr2 BB′O6 (B, B′=3d transition metal). The electronic structure calculations were based on density functional theory (DFT) with both generalized gradient approximation (GGA) and GGA+U approaches, where +U is on-site Coulomb interaction correction. With the consideration of 4 types of magnetic states, i.e. ferromagnetic (FM), ferromagnetic (FiM), antimagnetic (AF) and nonmagnetic (NM), we found 5 promising candidates for half-metallic (HM) materials: Sr2ScCrO6, Sr2TiCrO6, Sr2MnCrO6, Sr2ZnMnO6 and Sr2ZnFeO6. [Copyright &y& Elsevier]

Abstract: Electronic structures of the Co2FeAl(001) surface are studied theoretically via first-principles calculations based on density functional theory. It is found that the minority spin band gap at the Fermi level in bulk Co2FeAl disappears at the surface due to space localization of the states. However, beneath the surface, the density of states of individual atoms shows a trend of minority spin gap opening at the Fermi level, which indicates that the electronic structures become close to that of bulk Co2FeAl. The termination of FeAl is more favorable for spin polarization of Co2FeAl films than that of Co. Accordingly, we present a composite tri-layer model to illustrate the fading of the half-metallic property in Co2FeAl films against the ideal character in bulk materials. [ABSTRACT FROM AUTHOR]