Kristin Joy Duxstad

Commercial TMR heads for hard disk drives: characterization and extendibility at 300 gbit/in/sup 2/

Tunneling magnetoresistive (TMR) reading heads at an areal density of 80-100 Gbit/in/sup 2/ in a longitudinal magnetic recording mode have for the first time been commercialized for both laptop and desktop Seagate hard disk drive products. The first generation TMR products utilized a bottom TMR stack and an abutted hard bias design. These TMR heads have demonstrated three times the amplitude of comparable giant magnetoresistive (GMR) devices, resulting in a 0.6 decade bit error rate gain over GMR. This has enabled high component and drive yields. Due to the improved thermal dissipation of current-perpendicular-to-plane geometry, TMR runs cooler and has better lifetime performance, and has demonstrated the similar electrical static discharge robustness as GMR. TMR has demonstrated equivalent or better process and wafer yields compared to GMR. The TMR heads is proven to be a mature and capable reader technology. Using the same TMR head design in conjunction with perpendicular recording, 274 Gbit/in/sup 2/ has been demonstrated. Advanced design can reach 311 Gbit/in/sup 2/.

A superposed magnetic switching behavior in free layer of spin valves

Investigations on magnetization processes in spin-valves, consisting of two ferromagnetic metallic layers (a free layer which senses signals from media, and a pinned layer pinned by 8 pinning layer through a jntexfacial antiferromagnetic coupling) become increasingly important for head stability, especially at the recording density beyond 10 GWi’. In this paper we repm that a superposed magnetic switching behavior in the free layer, composed of an intrinsic uniaxial anisotropy and an interlayer exchange coupling Hex which may include both uniaxial and unidirectional anisotropies perpendicular to ABS [1][2], has been observed with MagnetoOptical Kerr BH imager (KerrBHi). The complex anisotropies in the free layer may be understnod as to the interlayer exchange coupling between the free layer and the pinned layer, i.e., anisompies displayed in the pinned layer will also be coupled into the free layer Impacts of this compound magnetic switching behavior in the free layer on spin-valve head design and process are also discussed.