Electronic structure, superconductivity, and magnetism in theC15compounds ZrV2, Zr

Abstract

We have calculated the self-consistent paramagnetic electronic structure of cubic Lavesphase ZrV2, ZrFe2, and ZrCo2, using the augmented-plane-wave method and the localdensity-theory form of exchange-correlation potential. Using the mean-field Stoner theory, we have determined the spin susceptibilities and magnetic moments of these compounds.We find that ZrV2 remains paramagnetic but with large Stoner enhancement, while the system Zr(Fel "Co")2is ferromagnetic for 0&x &0.5, in agreement with experiment. However, the Stoner theory yields an average magnetic moment which is generally much too small.The electron-phonon interaction has been calculated and, using estimates of the phononic properties from specific-heat measurements, we compare the theoretical estimates of the superconducting transition temperature with experiment. For ZrVq, we have found that it is crucial to account for the drop in density of states at the Fermi energy due to the structural phase transition in this material (cubic to rhombohedral at T -100 K). Estimates of this drop (-30%) have been obtained by analyzing the temperature-dependent spin susceptibility above and below T .

Hydrogen in Laves phaseZrX2(X=V,Cr, Mn, Fe, Co, Ni) compounds: Binding energies

“…This value is smaller than previous theoretical ones. 11,12 With hydrogen absorption (ZrV 2 H 0.5 ), there is a slight downward shift of the DOS profile with respect to the Fermi energy, which results in a lower N(E F ) by about 20% ͑see the inset of Fig. 3͒.…”

In situx-ray absorption study ofZr(V0.29Ni0.71Agostino1, Liberti2, Formoso3 et al. 2000Phys. Rev. B7120View full textAdd to dashboardCite

“…6 Band structure calculations on ternary alloys with the C15 Laves phase structure are not available. For a first look at band structure features and alloying effects, we make use of the augmented plane wave ͑APW͒ calculation performed by Klein et al 7 on ZrV 2 , ZrFe 2 , and ZrCo 2 . Some information on Zr(V 0.29 Ni 0.71 ) 3 bonding features and valence orbital hybridization can be deduced from their calculations because they deal with the same structure (C15) and similar elements.…”

“…In ZrCo 2 , Co d states are mostly confined in the valence band while hybridization between these states and Co p and Zr p and d states gives rise to a diffuse distribution of states. Thus, provided that the ZrNi 2 electronic features can be described by those of ZrCo 2 with accommodation of four extra electrons per unit cell, 7 we expect that the corresponding Ni states will maintain Co state characteristics apart from a shift to lower energies with respect to E F . In contrast, in the ZrV 2 density of states, V d states are localized in the conduction band while the hybridization with Zr states is particularly strong around E F .…”

Prediction of magnetic moment collapse in ZrFe2 under hydrostatic pressure

“…Zhang et al 11 calculated the electronic structure of it. Klein et al 12 discussed the electronic structure, superconductivity, and magnetism in ZrX 2 (X ¼ V, Fe, Co) with the C15 structures. Their results show that the Stoner theory is quantitatively inaccurate in these compounds because…”