Magnetic recording read head sensor technology

Since the invention of the hard-disk drive in 1956, the technology of the magnetic head sensor has never ceased to evolve. Today's sensors are drastically different from those used in these early heads; they can detect and transmit information from recorded data at densities greater than 200 Gbit/in 2 and data rates approaching 1 GHz. Numerous advances in nanomagnetics, magnetic ultrathin films, magneto-electronics, as well as device processing, have fueled the remarkable progress of this technology. An overview of the science and technology behind magnetic read head sensors is presented. The dimensional, geometrical and magnetic requirements for the heads are first described, followed by a description of the state of the art giant-magnetoresistive read sensors. We then discuss characteristics and potential advantages of next-generation read sensors, including current-perpendicular-to-plane tunnel-magnetoresistance and giant magnetoresistive sensors. The interplay between sensor properties, size requirements, process limitations and head performance is emphasized.