Magnetostress Effects in Evaporated Ni Films

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Abstract
The residual stress in 1000‐Å‐evaporated Ni films has been measured as a function of substrate temperature Ts. For Ts < 100°C, the stress is tensile and decreases with increasing Ts; at about 100°C, the tensile stress changes to compressive stress. As Ts increases beyond 100°C, the stress becomes increasingly compressive. A maximum in the compressive stress is observed at about 150°C, and then the stress decreases. Planar hysteresis loops obtained from a vibrating sample magnetometer show severely sheared loops for specimens under tensile stress; for specimens in compression the hysteresis loops are almost square. It has also been observed that the saturation magnetic moment of the films depends on the vacuum during deposition. Films deposited at a pressure of 10−7 Torr have larger moments than those prepared at 10−5−10−6 Torr. Although the magnetic moment depends on the degree of vacuum, the stress does not. Magnetic resonance and torque measurements show that the resonance field for the uniform mode, and the perpendicular anisotropy constant, can be directly correlated with the stress in these films. Recent reports of the anomalous behavior of the perpendicular anisotropy constant of Ni films with Ts are, therefore, actually due to the variation of the stress with substrate temperature.

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