First-principles investigations of atomic disorder effects on magnetic and structural instabilities in transition-metal alloys.

摘要: In this paper we use the coherent-potential approximation within Korringa-Kohn-Rostocker band-structure scheme to investigate influence of atomic disorder on magnetism and crystal structure transition-metal alloys like iron-nickel. This method allows an investigation disordered equally well-defined basis as corresponding stoichiometrically ordered phases. particular have calculated magnetic structural binding surfaces fcc ${\mathrm{Fe}}_{\mathit{x}}$${\mathrm{Ni}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$ for concentrations close critical concentration x=0.65 which corresponds Invar alloy ${\mathrm{Fe}}_{65}$${\mathrm{Ni}}_{35}$, with help fixed-spin-moment method. We find that in ground state gradually vanishes go from ${\mathrm{Fe}}_{60}$${\mathrm{Ni}}_{40}$, has a being separated nonmagnetic by 1.0 mRy/atom, ${\mathrm{Fe}}_{75}$${\mathrm{Ni}}_{25}$ is nonmagnetic. The criical driven magnetic-nonmagnetic transition occurs x\ensuremath{\approxeq}0.65--0.70 accordance phase diagram ${\mathrm{Fe}}_{\mathit{x}}$${\mathrm{Ni}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$. These calculations be compared ab initio ${\mathrm{Fe}}_{3}$Ni; here 1.25 mRy more stable than state. different behavior phases can explained statistical grounds. Furthermore, unstable respect martensitic fcc\ensuremath{\rightarrow}bcc Fe-rich side furthermore temperature evolution finite-temperature fluctuation theory. interesting reentrant ferromagnetic transitions x=0.65.