Crystal distortion and magnetic structure of γ-MnM(M = Fe, Cu, Zn) alloys

Abstract

We conducted X-ray and neutron diffraction experiments and magnetic susceptibility measurements for γ-MnFe alloys with a small amount of Cu or Pt, and for γ-MnCu and γ-MnZn alloys. γ-(Mn 1-xFe X) 0.95Cu 0.05 alloy with x = 0.26 around 10 K shows a face-centered orthorhombic structure with a = 0.3681, b = 0.3655 and c = 0.3622 nm, and a non-collinear antiferromagnetic structure with μ a = 0 and μ b/μ c = 0.62. With increasing temperature, orthorhombic-tetragonal with c/a> 1 structural transition occurs at T 0 ( = 125 K) and the tetragonal structure finally transforms to a cubic structure at T t( = 352 K), which is lower than the Néel temperature T N( = 440 K). The γ-(Mn 1-xFe x) 0.95Pt 0.05 alloy with x= 0.13 at 10 K also shows a similar structure with a = 0.3745, b = 0.3714 and c = 0.3649 nm, which has a non-collinear antiferromagnetic structure with μ a = 0, μ b = 1 -03 and μ c = 1.65 μ B/ (Mn or Fe) atom. However, the γ-Mn 1-xCu x alloy with x≤ 0.26 and γ-Mn 1-xZn x alloy with x ≤ 0.28 show a tetragonal structure with c/a < 1 at low temperature. © 2005 The Japan Institute of Metals.