Amorphous magnetism in iron-boron systems: First-principles real-space tight-binding LMTO study.

Abstract

We have performed ab initio spin-polarized self-consistent calculations of the electronic structure and magnetic moments in the series of the ${\mathrm{Fe}}_{100\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{B}}_{\mathit{x}}$ glasses (0x60) with the real-space tight-binding LMTO method. Realistic atomic models consisting of 500 to 864 atoms in a cubic box with periodic boundary conditions were constructed with the use of the Monte Carlo method. The systems studied show itinerant magnetism with the net magnetic moment on iron sites, \ensuremath{\mu}\ifmmode\bar\else\textasciimacron\fi{}, saturating at the maximum value in a region of a (hypothetical) amorphous iron. The iron magnetic moment decreases upon dilution with boron atoms with no maximum on the compositional dependence of \ensuremath{\mu}\ifmmode\bar\else\textasciimacron\fi{}. The calculated distribution of the iron moments is narrow with the width decreasing towards the boron-rich end of the series. The magnetovolume effect is shown to be noticeable in iron-rich glasses, declining with increasing boron content. No evidence of a tendency to form the spin-glass state has been found in iron-rich borides.