HITPERM soft-magnetic underlayers for perpendicular thin film media
نویسندگان
چکیده
A class of nanocrystalline alloys, HITPERM ~Fe, Co!–M–B–Cu (M5Zr,Hf,Nb, etc.! found to exhibit excellent soft-magnetic properties is being studied for use as a soft-magnetic underlayer for perpendicular recording media. Previously, we reported that HITPERM films of ;100 nm thickness sputtered at room temperature ~RT! and at ;2.3 W/cm power density had exhibited an amorphous microstructure, which had turned mixed nanocrystalline when prepared at ;250 °C. However, nanoparticles of FeCo have now been crystallized even at RT without the application of heat, by increasing the sputtering power density to ;4.5 W/cm. This dramatically improved the 4pM s while still maintaining a low coercivity. There was a further slight increase in the 4pM s at ;6.8 W/cm. Moreover, these soft-magnetic properties were maintained even when the substrate temperature was subsequently raised to ;250 °C. Transmission electron microscopy studies showed the presence of relatively small nanocrystals of the ferromagnetic a8-FeCo ~or a-FeCo! phase alone, for both sets of films. Previously, we had reported that the CoCrPt magnetic layer grew with a strong ~00"2! texture on amorphous HITPERM. We have now seen that with a thin Ti intermediate layer ~;5 nm! the CoCrPt layer maintained a strong ~00"2! texture even on the nanocrystalline HITPERM. Thus, due to their particular nanocrystalline nature, these HITPERM films exhibit much better soft-magnetic properties, while still leading to strong ~00"2! texture on the CoCrPt magnetic layer. © 2003 American Institute of Physics. @DOI: 10.1063/1.1558091#
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