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By | Chris Mellor 1st October 2008 09:26

TDK tunnels through hard drive areal density record

Achieves 803Gb/in²

TDK researchers have achieved an areal density record of 803Gb/in² potentially extending the life of current read/write head technology.

The higher the areal density the more data can be packed onto a disk drive. According to reports, TDK hard disk drive (HDD) read/write heads boffins used a disk platter from Showa Denko K K based on perpendicular magnetic recording with discrete track recording (DTR) superimposed on top of it. The TMR (Tunneling Magneto-Resistance) read/write head had its magneto-resistance uprated by more than 80 per cent with the TMR element's bond resistance kept low.

Heads need to shrink to cope with the narrower tracks and smaller bit sizes on HDD platters as areal densities increase. As they become smaller the electrical resistance of the TMR element increases, and this makes reading the bits harder.

Advanced technology CPP-GMR (Current-Perpendicular-to-Plane Giant Magneto-Resistance) heads have lower resistance and are seen as TMR replacements for areal densities greater than 600Gbit/sq in or so. The TDK researchers have pushed this transition to CPP-GMR heads out to much higher areal density levels.

Their achievement exceeds that implied in statements coming out of Hitachi GST regarding TMR heads which foresaw them coping up to 625Gb/in² areal densities with CPP-GMR (Current-Perpendicular-to-Plane Giant Magneto-Resistance) heads being used to progress to terabit areal density levels.

Katsumichi Tagami, the director of TDK Technology's SQ Research Center, thinks that a 1Tbit/sq in areal density can be managed with TMR heads. It is cheaper for the HDD industry to use existing TMR head technology than move to newer CPP-GMR technology. ®

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