Monitoring the Magnetostriction of Thin Films During Vacuum Deposition

Abstract

A device has been constructed which monitors the magnetostriction of magnetic films prepared by vacuum deposition techniques. The substrate upon which the film is deposited is stressed mechanically during deposition, thereby applying alternate tensile and compressive states of strain to the depositing film. A localized alternating magnetic field is employed as an anisotropy orienting field and is used also to switch the state of magnetization of the film. The substrate is strained at a low repetition rate, and the depositing film is switched magnetically at a high rate. The periodic stress application to the film and the associated strain‐induced anisotropy modulate the flux reversal output; the resulting signal is detected by a pickup coil. The phase and amplitude of the modulated signal are a function of the magnetostriction and the corresponding film composition. The monitor is mounted in the vapor path so that a representative film element is deposited on the stressed substrate. Zero magnetostriction of the sample, as determined by the monitor, has been found to correspond to zero magnetostriction of arrays of film elements deposited at the same time. The monitor makes possible automatic control of magnetostriction through control of source composition.