Influence of inert gas incorporation on uniaxial anisotropy of sputtered GdCo thin films

Abstract

A study was made of the gas content and uniaxial anisotropy of GdCo films as a function of bias voltage and gas pressure. Unlike previous studies of GdCo, in this investigation, a multi-target sputtering system was used, making it possible to keep the Gd/Co ratio (and hence 4πM) relatively constant while the bias and pressure were varied. For low bias voltages, the anisotropy was found to increase with bias as has been reported in the literature. However, unlike previous studies, we found that the anisotropy reached a peak value at ∼200 V and then decreased with bias at higher voltages. When argon was used as the sputtering gas, it was found that the gas content in the film also peaked at ∼200 V; with neon, the gas content did not peak but decreased with bias at voltages over ∼100 V. Samples deposited with an argon pressure of 50 mTorr show an approximate proportionality between anisotropy and gas content, suggesting that the presence of the gas is at least partly responsible for the generation of growth-induced anisotropy in GdCo films.