Magnetic properties and microstructure of CoCr and CoCrTa thin films sputtered at high pressure on a PET substrate

Abstract

Thin magnetic films (CoCr/Cr, CoCrTa/Cr and CoCrTa/Cr/SiO) are deposited by DC-magnetron sputtering on a PET substrate. The optimum sputter pressure, giving rise to the highest coercive force, is found to be around 50 mTorr. However, the deposition parameters influence the value of this optimum pressure. The addition of Ta to CoCr leads to phase segregation, resulting in CoCrTa films in which the magnetic interaction between the grains is more dipolar than in CoCr films. The magnetic interactions in CoCrTa films are less dependent on the sputter parameters than those in CoCr films. The evaporation of a seedlayer of, e.g. SiO prior to the deposition of the Cr underlayer increases the coercive force of the CoCrTa thin films, especially when the CoCrTa layer is thinner than 50 nm. This makes these films more suitable for high-density magnetic recording.