Head and Media Challenges for 3 Tb/in $^{\boldsymbol {2}}$ Microwave-Assisted Magnetic Recording

A specific design for microwave assisted magnetic recording (MAMR) at about 3 Tb/in
$^{2}$
(0.47 Tb/cm
$^{2}$
or 4.7 Pb/m
$^{2}$
) is discussed in detail to highlight the challenges of MAMR and to contrast its requirements with conventional perpendicular magnetic recording (PMR). In particular, it has been determined that MAMR-optimized media should have: higher damping than today's PMR media upon which ferromagnetic resonance measurements are reported, very low intergranular exchange coupling, and somewhat stronger layer to layer exchange coupling. It was found that with exchange-coupled composite type media (i.e., graded anisotropy with controlled exchange), a spin torque oscillator in the write gap of a wider shielded pole cannot adequately define the written track at high track density. Adequate lateral field gradient, however, is achieved by modifying the pole tip geometry. Other details of this conceptual design are also discussed.