Magnetic anisotropy in dc diode getter sputtered GdCo films—How important is the argon content in the films?

Amorphous magnetic GdCo films were prepared by a dc diode getter sputtering technique with no bias field applied to the substrate during the film growth. Films (type I) obtained using 1.0 kV and 60 mTorr Ar during the sputtering show perpendicular anisotropy with Keffu =1.5×105 erg/cm3. Films (type II) deposited at 2.0 kV and 28 mTorr Ar exhibit magnetic isotropy with Kinu≊0. However, the actual argon content in the type II films is three times of that in the type I films. Nevertheless, the argon impurity in both the type I and type II films is ≤1.0 at. %, which is far less than those obtained in the biased rf diode sputtered GdCo films. Also, the distribution of argon is uniform in the film as observed from the Rutherford backscattering spectrometry.