Investigation of the Effect of O2, N2, and H2O on Nickel Thin Films

Abstract

The role of oxygen, nitrogen, and water vapor adsorbed during the evaporation process was investigated for nickel films grown on room-temperature glass substrates. A change in pressure from 10−10 to 10−7 Torr oxygen caused a marked shift in the resonance field and the perpendicular anisotropy (i.e., the anisotropy resulting from the rotation of the magnetization out of the plane of the film). This shift could be accounted for by an increase in internal stress from 5×109 dyn/cm2 at 10−10 Torr to 2×1010 dyn/cm2 at 10−7 Torr. The wall-motion coercive force also increased with increasing pressure, ranging from 50 to greater than 200 Oe. Samples made in pressures as high as 1×10−5 Torr nitrogen appeared identical (as determined by the measurements) to films made in residual vacuum of 10−10 Torr. The presence of water vapor caused a slight increase in internal stress and Hc when the pressure changed from 10−10 to 10−5 Torr. The effect appears to be related to an internal oxidation phenomenon. These experiments clearly demonstrate the role of impurity atoms in determining the stress-sensitive magnetic properties of films and emphasises the need for controlling the partial pressures of gases during evaporation, and not just the total pressures.