Materials Challenges for Next-Generation, High-Density Magnetic Recording: Media and Read Heads
The hard disk drive industry is making continuous efforts to increase the areal density of magnetic recording. To realize an areal density of higher than 2 Tbit/in2 in the future, both media and readers need technical breakthroughs. Since the bit size will be in the range of 20 nm, the magnetic grains in the recording media must be reduced to less than 6 nm, requiring the use of ferromagnetic materials with high magnetocrystalline anisotropy such as L10 FePt. The shield-to-shield spacing of read sensors must also be smaller than 20 nm with low device resistance (resistance-area product RA 0.5 m2), which is very difficult to achieve using MgO based tunneling magnetoresistance devices.
In this talk, we will address the materials challenges to the realization of an ideal media nanostructure using L10 FePt for heat-assisted magnetic recording (HAMR) media and narrow readers for > 2 Tbit/in2 areal density. Recently significant progress has been made in current-perpendicular-to-plane giant magnetoresistive (CPP-GMR) devices using highly spin-polarized Heusler alloy ferromagnetic layers and new spacer materials. The very high magnetoresistance ratios achieved in CPP-GMR are encouraging for future read head applications of CPP-GMR, or its laterally extended version, lateral spin valves. The devices with high magnetoresistive output at low RA may open new
applications in addition to disk read heads.