Solving the Data Density Challenge

In a magnetic disk drive, digital information is written on tiny magnetic bits. The drive's head produces a magnetic field that orients the bit's magnetization in a particular direction, representing either 0 or 1.

Longitudinal Recording The magnetization of the bits is usually parallel to the direction in which the head is moving relative to the disk. To pack more data into the disk, smaller bits are put closer together. At some point, the bits may become so small that thermal energy may cause it to demagnetize -- a phenomenon known as superparamagnetism. To combat this, manufacturers have been increasing the coercivity (the "field" required to write a bit) of the disks they produce.

Perpendicular Recording Rather than parallel, the magnetization of the bits is perpendicular to the disk. This allows recording at a higher density because it can produce higher magnetic fields in the recording medium.

Hybrid Recording Optically or thermally assisted magnetic recording uses lasers to produce a hot spot on the media, while data is being written magnetically. When the media is heated, the coercivity, or field required to write on the media is reduced. This makes it possible to write to high-coercivity media that have a higher stability against superparamagnetism.