GMR and soft magnetic properties of Ni-Mn alloys with dispersed ferromagnetic nano particles

GMR and soft magnetic properties were investigated in nano-scale inhomogeneous Ni_1-xMn_x alloys (x = 0.20∼0.30), where ordered single-domain particles are distributed in disordered nonmagnetic or Ni-rich or Mn-rich matrices. The GMR of Ni₃Mn alloy depends on the volume fraction of ordered domains ε. Maximum value of -1.8% is obtained at ε ∼ 0.2. Moreover, the GMR depends remarkably on x: GMR for 0.20 ≤ x ≤ 0.24 is small (Type I) and for 0.26 ≤ x ≤ 0.30 has a maximum of -6% at x = 0.30 (Type II . Types I and II are caused respectively by ferromagnetic and antiferromagnetic interactions between domains.