Transmission electron microscopy study of CoFe films with high saturation magnetization

Transmission electron microscopy (TEM) has been used to study magnetization processes in four high moment CoFe films. While all films were of similar total thickness, 50nm, the differences between them were the inclusion or otherwise of a seed layer and the introduction of nonmagnetic spacers to form laminated films. The detailed reversal mechanism for easy and hard axis reversals of each film was investigated. As expected cross-tie walls were observed in the films with thicker CoFe layers and wall displacements between layers were seen with the introduction of one or more spacer layers. Magnetization dispersion was reduced as multilayering was introduced. In the laminated film with three spacer layers, defect areas where the local magnetization distribution differed markedly from the surrounding film were observed. Cross-sectional TEM showed that layer roughness increased through the stack and this was the probable cause of the localized magnetic anomalies.