Inductive write heads using high moment FeAlN poles

This paper reviews the material properties of Fe-AlN high moment soft magnetic material, and discusses the design, fabrication and performance of write heads using this material. These write heads comprise two designs. The first had FeAlN for both top and bottom poles. The second incorporated a 0.2 μm thick FeAlN layer underneath an electroplated Ni₈₀Fe₂₀ top pole. The first type of head was tested on high coercivity (3300 Oe) media. Wide and narrow track width heads saturated the media at the highest tested write frequency of 225 MHz. At 90 MHz, they exhibited overwrite approaching 50 dB and hard transition peak shift of less than 1 nm. This overwrite was 7-9 dB higher than that measured for heads with Ni₄₅Fe₅₅ top poles. A 50% amplitude roll-off density (D₅₀) of up to 6300 fc/mm was also measured, using a narrow gap MR read sensor. However, reverse dc erase noise measurements indicated significantly lower head efficiency compared to NiFe heads, as has been observed previously. The second type of head on the other hand exhibited ~5 dB better overwrite compared to a Ni₈₀Fe₂₀ head, without a large loss in head efficiency