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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]. Index Terms--Areal density, disk drives, electrical static discharge (ESD), longitudinal recording, noise, perpendicular recording, reliability, signal-to-noise ratio (SNR), tunneling magnetoresistive (TMR) heads.

A full three-dimensional (3-D) self-consistent micromagnetic code has been employed to design an unshielded perpendicular writer for an areal density of 1 Tb/[in.sup.2]. The head consists of a probe-type tip protruding from a collar. The tip has saturation magnetization (Ms) of 24 kG while the collar has lower Ms. The magnitude and orientation of anisotropy field ([H.sub.k]) in the tip is varied to obtain the best recording performance. The combination of high anisotropy write tip with low Ms collar is shown to produce effective write fields in excess of 19 kOe and less than 20% track erasure for [10.sup.7] passes. Introduction of in-plane anisotropy within the pole tip reduces head remanence sufficiently that on-track erasure exceeds a benchmark of [10.sup.8] passes. The damping constant in Landau--Lifshitz--Gilbert equation has been varied to improve the frequency response. With damping constant equal to 1.0, simulations show that the head is capable of switching in approximately 0.15 ns. Index Terms--Adjacent track erasure, on-track erasure and frequency response, perpendicular recording.

A strategy for high-density perpendicular magnetic recording with a soft underlayer is introduced. The approach is based on three concepts: 1) the nonzero magnetic susceptibility of the recording layer; 2) the use of intergranular exchange to partially cancel magnetostatic effects; and 3) a novel head architecture. Micromagnetic simulations involving recording head, soft underlayer, and recording layer are employed to specify a particularly advantageous design. It is shown that the expected density approaches 1 Tbit/[in.sup.2]. Index Terms--High-density perpendicular recording, intergranular exchange, micromagnetics, permeability.

A perpendicular recording head for an areal density of 1 Tbit per square using a self-consistent three-dimensional (3D) micromagnetic model is discussed. Finally simulations show that a high perpendicular H(sub k) reduces the flux spreading from the narrow tip, therefore it enhances the recording field.

Tunneling magnetoresistive (TMR) reading heads at an areal density of 80-100 Gbit/in² 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 Gbitfin2 has been demonstrated. Advanced design can reach 311 Gbit/in² [ABSTRACT FROM AUTHOR]

Tunneling magnetoresistive (TMR) reading heads at an areal density of 80-100 Gbit/in² 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 Gbitfin2 has been demonstrated. Advanced design can reach 311 Gbit/in² [ABSTRACT FROM AUTHOR]