Magnetically soft, high saturation magnetization laminate of iron-cobalt-nitrogen and iron-nickel for perpendicular media underlayers

摘要

A magnetic disk includes a substrate, a soft magnetic underlayer disposed over the substrate, and a media layer disposed over the underlayer. The underlayer includes a first plurality of layers each containing NiFe having an atomic concentration of iron that is at least about thirty percent. The underlayer further includes a second plurality of layers that is interleaved with the first plurality of layers. The second plurality of layers each contain FeCoN having an atomic concentration of iron that is greater than an atomic concentration of cobalt, and having an atomic concentration of nitrogen that is less than the atomic concentration of cobalt. The atomic concentration of nitrogen is less than eight percent. The media layer contains a magnetically hard material having an easy axis of magnetization oriented substantially perpendicular to both the media layer and the underlayer.