Disk read-and-write head

The flying height of the head is controlled by the design of an air bearing etched onto the disk-facing surface of the slider.

The role of the air bearing is to maintain the flying height constant as the head moves over the surface of the disk.

When reading, the magnetized material rotates past the heads, the ferrite core concentrates the field, and a current is generated in the coil.

Thin layers of magnetic (Ni–Fe), insulating, and copper coil wiring materials were built on ceramic substrates that were then physically separated into individual read/write heads integrated with their air bearing, significantly reducing the manufacturing cost per unit.

The separate read element uses the magnetoresistive (MR) effect which changes the resistance of a material in the presence of a magnetic field.

These MR heads are able to read very small magnetic features reliably, but can not be used to create the strong field used for writing.

[6] The introduction of the AMR head in 1990 by IBM[7] led to a period of rapid areal density increases of about 100% per year.

The same thermal actuation approach can be used to temporarily decrease the separation between the disk medium and the read sensor during the readback process, thus improving signal strength and resolution.

A hard disk head and arm on a platter
Microphotograph of a hard disk head. The size of the front edge is about 0.3 * 1.2 mm. The functional part of the head is the round, orange structure in the middle. Also note the connection wires bonded to gold-plated pads.
Read–write head of a 3 TB hard disk drive manufactured in 2013. The dark rectangular component is the slider and is 1.25 mm long. The platter surface moves past the head from right to left.