Abstract
As the recording industry increases areal density every year, a magnetoresistive-soft adjacent layer (MR-SAL) head design is desirable with the following qualities: easy to be fabricated in large volume, capable of consistent and stable device-to-device performance, and enough signal to noise ratio to perform at high recording densities and data rates. A new type of MR head with these attributes is described for an areal density equal to 1444 Mb/in.(2). The off-track characteristics of this MR head are determined by the sensor edge design which is defined by a permanent magnet (PM) layer. Improved off-track performance was achieved by substituting the spacer layer with the PM outside of the active sensor area. Excellent boundary control stabilization was obtained by the ferromagnetic exchange coupling between the PM and, the SAL and the MR layers. The bit error rate and electrical test results showed acceptable performance at 175 kbpi and 8250 tpi. The above MR head had average values of low frequency amplitude (LFA), PW50, read width and write width equal to 900 mu V, 12.4, 72, and 107 mu in., respectively. The low frequency symmetry (LFSYM) was 1.1 (Vpos/Vneg) and the position error off-track capability was 26 mu in. Finally, the LFA covariance (sigma/avg) was found to be 0.22% and the microtrack had no bumps or side lobes. These results indicate that this design and its implementation produce stable heads that can perform on and off track at 1444 Mb/in.(2). (C) 1997 American Institute of Physics.