Physica B 350 (2004) e1103–e1106 Collective excitations in Ni 62 Nb 38 glass from partial scattering functions G.F. Syrykh a, *, A.S. Ivanov b , J. Stride b , M.G. Zemlyanov a a RRC Kurchatov Institute, Moscow 123182, Russian Federation b ILL, 6 rue Jules Horowitz, F-38042 Grenoble, France Abstract The inelastic neutron scattering intensity, I ðE; OÞ; for Ni 62 Nb 38 metal glass has been measured over a wide range of scattering angles, O ¼ 13  2120  , and energy transfer, E ¼10–+50 meV. Three samples with the same chemical composition and different Ni isotope content have been investigated. This allowed us to reconstruct three partial inelastic scattering functions I NiNi ðE; OÞ; I NbNb ðE; OÞ; and I NiNb ðE; OÞ; according to the Ashcroft–Langreth formalism. The propagating excitations in a two-component amorphous alloy are the result of the superposition of three partial excitations. Each of these excitations is given by the corresponding partial atomic distribution. The ‘‘acoustic-phonon- like’’ dispersion relation is observed up to Q ¼ 6:5A 1 , which is the limit accessible in the present experiment. r 2004 Elsevier B.V. All rights reserved. PACS: 63.20.Dj Keywords: Metal glass; Atomic dynamic; Inelastic neutron scattering; Isotope substitution; Partial functions 1. Introduction The relationship between the short-range struc- tural order and atomic dynamics of disordered systems has attracted interest because of the possibility of the existence of structure-induced peculiarities in the vibration modes and density of states. Inelastic neutron scattering (INS) is a powerful tool for the investigation of collective excitation in condensed matter. This technique has been used to investigate the generalized dispersion relation in several metallic glasses (Mg 70 Zn 30 , Ni 24 Zr 76 , Fe 85 B 15 and Ni 63 Zr 33 [1–4]). However, metallic glasses have at least two component systems and more detailed information is contained in the partial structure dynamic correlation functions, S AB ðQ; EÞ [5]. The INS experiment provides us with a possibility to get unknown functions by means of the isotope contrast in neutron scattering. The total dynamic structure factors which can be obtained from the neutron scattering experiment is given in terms of a weighted sum of partials /bS 2 SðQ; EÞ¼ X A;B c A c B b A b B S AB ðQ; EÞ: ð1Þ ARTICLE IN PRESS *Corresponding author. Tel.: +7-095-196-99-08; fax: +7- 095-196-59-73. E-mail address: sgf@isssph.kiae.ru (G.F. Syrykh). 0921-4526/$ - see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.physb.2004.03.300