Irradiation Damage in Fe-Co Thin Films With Low-Energy Ion Beam

The authors estimated the effect of ion-beam irradiation damage on saturation magnetic flux density (
B

_s
) in Fe-Co thin films, a material expected to be used as a main pole in write heads in the era of Tbits/in
²
recording density. Fe-Co thin film deposition and successive ion-beam irradiation at 250 eV and a capping layer deposition were performed in the same ion-beam etching apparatus without breaking vacuum. The etching tests revealed
B

_s
of the films with thickness of about 10 nm was decreased by the ion-beam irradiation; about 0.1-0.2 T decrease in
B

_s
was observed with several nanometers etching. Regardless of etching depth, about 0.1 T decrease in
B

_s
would appear even in the case of shallow etching of about 1 nm. Damage control in the main pole fabrication would be one of the important issues for the write heads.