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-x Fe x ) 0.95 Cu 0.05 alloy with x = 0.26 around 10K shows a face-centered orthorhombic structure with a = 0.3681, h = 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 > I structural transition occurs at T o (= 125K) and the tetragonal structure finally transforms to a cubic structure at T t (= 352 K). which is lower than the Neel temperature T N (= 440K). The γ-(Mn 1-x Fe x ) 0.95 Pt 0.05 alloy with x = 0.13 at 10K 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 = 1.94μ b /(Mn or Fe) atom. The γ-Mn 1-x Cu x alloy with x ≤ 0.26 and γ-Mn 1-x Zn x alloy with x ≤ 0.28 show a tetragonal structure with c/a < I at low temperature.