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M: Metallphysik

M 30: Elektronische Eigenschaften

M 30.5: Fachvortrag

Thursday, March 29, 2001, 18:15–18:30, S5.3

Ordering Effects in Invar Alloys — •V. Crisan¹, P. Entel¹, and H. Akai² — ¹Gerhard-Mercator-Universität Duisburg, D-47048 Duisburg — ²Osaka University,Osaka 560-0043, Japan

We investigated in detail the influence of atomic short-range order on the properties of Fe–Ni, Fe–Ni–Co and Fe–Pt alloys by using the Korringa-Kohn-Rostocker CPA method. The allowance for inequivalent lattice sites in the fcc unit cell enables us to describe the importance of ordering tendencies in the alloys. It turns out that the common feature of all Invar alloys is microscopically related to an intrinsic magnetovolume instability at T = 0 being most pronounced for a certain value of the short-range order parameter, and to the t₂g–e_g scenario with increasing temperatures, in all ordered and disordered Invar alloys. The atomic short-range order scales to a large extent all magnetic and nonmagnetic properties.