REAL-SPACE TB-LMTO SPIN-POLARIZED SELF-CONSISTENT CALCULATIONS OF THE ELECTRONIC-STRUCTURE OF THE AMORPHOUS-ALLOYS NI-B, FE-B AND ZR-BE

The first-principles tight-binding (TB)-LMTO method is used for self-consistent calculations of the electronic structure of the amorphous Fe80B20, Ni100-xBx and ZrxBe100-x alloys in combination with the recursion method. Realistic structure models were constructed with the use of the Monte Carlo method. The electron density has been calculated self-consistently for the given amorphous structures. We describe our results for the electronic structure of amorphous Fe80B20, Which is a typical transition-metal-metalloid glass. In the paramagnetic phase it has a generic double-peak structure close to the Fermi level formed by non-bonding Fe d orbitals, with a bonding B p-Fe d hybrid at lower energies, in agreement with previous calculations. We present the spin-polarized LSDA calculations, which show that the d band splits, resulting in a strong itinerant magnetism in Fe80B20 With a net moment on Fe atoms of muBAR = 2.14mu(B), in good agreement with experiment and estimated values from generalized Stoner criteria. The Dos in a-Ni100-xBx has a shape similar to that of paramagnetic Fe80B20 shifted downwards from the Fermi level, which explains the paramagnetic behaviour of all studied Ni-based glasses (x=20, 25 and 34). With increasing B content the height of the main Dos peak formed by the Ni d electrons decreases and the strength of the covalent Ni d-B p interaction increases. In Ni-rich glasses the onset of ferromagnetism corresponds to a B concentration below some threshold and the present LSDA calculations predict a net moment muBAR = 0.43 mu(B) in pure a-Ni. Comparison of the Dos with photoemission data indicates that the calculated Ni d band in Ni80B20 is shifted downwards by 0.25 eV and broadened by 1.1 eV as a result of the local density approximation, where non-locality and dynamic correlations are lacking. The calculated Dos in a-ZxBe100-x is dominated by the broad Zr d band. In all studied glasses a significant hybridization between transition metal d and metalloid/simple-metal p states takes place. By making use of low-temperature heat capacity and magnetic susceptibility data for Ni-B and Zr-Be glasses we show a good agreement with the calculated Dos at the Fermi level, N(0), if electron-phonon and exchange enhancements are taken into account.