The technology which increases recording density bythe fact thatthe IBM corporation developed, puts ruthenium layer to the record aspect of the hard disk.To increasethe capacityper disk area of the hard disk, magnetic density should have been made high, but when magnetic densityis increased above a certain limit, the super magnetic effect (superparamagnetic effect) with the phenomenon which is calledoccurs, the data the long period of time is stabilized andit becomes impossible to retain.This limit per 1 square inch is called 20 - 40Gbit,the present harddisk almost has reached to this limit. But, with AFC media technology it broke this limit by the fact that polar thin ruthenium layer is put in magnetic layer, it succeeded in pushing up the upper limit of magnetic density. ... The continuation is readAlready, thistechnology is usedby the same company make hard disk, per 1 square inch achieves the memory density of 25.7Gbit.Per 1 square inch we designate 100Gbit as goal in the future, it has estimated thatthe product whichby 2003inthe desktop PCwith 400GB andnotePC had the capacity of 6GB at 200GB and 1 inch Microdrive is sold. The hard disk tominiaturizatione conomicalelectric power from the fact that it can convert, the notebook PC andthe voice which expectstheapplicationin PDA field is strong even at the same capacity.Furthermore,as forthe researcher of IBM because the ruthenium layer which is used for this technology was called "PixieDust", taking the name, there are also times when it is called "Pixie Dust technology".