Permanent magnet stabilization of an overlaid MR head

Higher area density in the rigid disk magnetic recording industry is being achieved with magneto-resistive (MR) heads biased with a soft adjacent layer (SAL). The abutted and the overlaid designs are the two approaches most commonly used. Reader stability is a result of a single domain structure due to boundary control stabilization (BCS) from exchange or magnetostatic coupling. The details of a particular design determine on track and off track performance. Recent reviews and products suggest that the magnetostatically coupled abutted head design is superior to published overlaid designs. This paper describes the electrical performance and physical characteristics of another overlaid design that performs on track and off track at the recording density of 650 Mb/in²