Thin Film Heads are made just like semiconductor chips and use a method of sputtering iron and nickel on hard aluminum. They allow a very narrow head gap adn are four times more magnetic than Ferrite heads. They have a standard thin film head for writing and a special magneto-resistive head for reading. Having two heads also allows each head to be optimized to its task. Mr heads operate as follows, the resistance of a current carrying magnetic conductor changes when an external magnetic field is present.
Normal heads produce a voltage when detecting magnetic field flux reversal.
MR heads sense a flux reversal and changes resistance. A small current flows thru the heads and the change in resistance is measured by this sense current. MR heads are three to four times more powerful than a thin film head during a read. Besides the heads there is the Head Actuator Mechanism, which moves the heads across the disk and positions them over the desired cylinder. There are 2 basic types of head actuators, stepper motor type and voice coil type.