Read Write Heads
The read/write heads are U-shaped pieces of conductive material. Hard disks have parallel tracks across the width of the media and the read/write heads take time to switch between tracks and to scan within tracks. Different spots on the storage media take different periods of time to access. For a hard disk this time is typically less than 10 ms. Defragmentation of the hard drive can improve the performance of a computer.
Types of heads used in hard disk design
Giant Magneto-Resistive (GMR) Heads
In 1997 IBM introduced the giant magneto-resistive (GMR) head. These are structured as a space layer of non magnetic material between two magnetic layers. Manganese Ferrite (MnFe) is used as an exchange film.