Effect of surface cleaning of substrate on the exchange coupling field in Ni-Fe/25at%Ni-Mn films

The effect of surface cleaning of Si(100) substrate on the exchange coupling field, H/sub ex/ was investigated for Ni-Fe/25 at% Ni-Mn films. H/sub ex/ measured at room temperature rapidly increased when the substrate surface was slightly (about 10 /spl Aring/) etched by RF plasma just before film deposition, especially in the films with very thin (50 /spl Aring/) Ni-Fe layer. From structural analysis of the films, and view of the temperature dependence of H/sub ex/, it was concluded that the increase of H/sub ex/ was caused by the enlargement of /spl gamma/-Ni-Mn grains epitaxially grown on the underlying Ni-Fe grains.