Development of Spin-Torque Oscillators and High ${K}\!_{{u}}$ CoPt Media With Small Grain Size for Microwave-Assisted Magnetic Recording

We report the selection of materials and design of spin-torque oscillators (STOs) which are able to operate in an alternative magnetic field (variable frequency) of magnitude ~8000 Oe, generate large enough in-plane ac magnetic field in the recording media, and have tunable high frequency at low driving current for microwave-assisted magnetic recording (MAMR) based on micromagnetic simulations. The mechanism and integration approaches of STOs with the current recording system to have the least driving current are also presented. This paper also covers the material choice, layer-stack optimization, and process development on Co
_x
Pt
_1-x
alloy films with extremely high coercivity of more than 1.5 T (K
_u
of about 1.5 × 10
⁷
erg/cc), well-isolated small grains of size 6-7 nm, for the extension of perpendicular magnetic recording and MAMR.