Tunneling magnetoresistive heads beyond 150 Gb/in2

Tunneling magnetoresistive (TMR) readers capable of 150 Gb/in² of areal density magnetic recording for hard disk drive were demonstrated with bit-error-rate performance. The head design used is basically a bottom type stack of Ta/PtMn/CoFe/Ru/CoFe/oxide barrier/CoFe/NiFe/Ta cap with abutted hard bias stabilization. The electrical reader width is about 4 μ´´ to reach a very high track density and shield-to-shield spacing is about 700 Å for high linear density. On-track bit error floor is better than 10^-5 at a linear density of 900 KBPI and the recording system noise is dominated by the media. The best areal density achieved (using -4 OTC reference level) is 143 Gb/in² using symmetric squeeze and 152 Gb/in² using asymmetric squeeze method, respectively. It was found that the TMR head has several decibels more signal-to-noise ratio gain over spin valve readers at 150 Gb/in² and beyond. The TMR head is also suitable for perpendicular recording application.