L12 phase formation and giant exchange anisotropy in Mn3Ir/Co-Fe bilayers

The degree of order S of Mn-Ir layers and the exchange anisotropy of Mn-Ir/Co-Fe bilayers were investigated for various chemical compositions of Mn-Ir layers, underlayer materials, and underlayer thicknesses. It was found that: (1) The compositional range over which L1(2)-phase Mn3Ir could be formed is 22-32 at% Ir and giant exchange anisotropy is obtained in this range. (2) Ru is favorable as an underlayer material for avoiding interdiffusion with the Mn-Ir layer during deposition on the temperature elevated substrate. (3) The underlayer thickness could be reduced to 5 nm while maintaining a giant exchange anisotropy in excess of 1 erg/cm(2). (C) 2006 Elsevier B.V. All rights reserved.