Comparison of MR and GMR spin-valve heads for magnetic recording on MP tape

Abstract

Summary form only given. The use of the giant magnetoresistive (GMR) spin valve (SV) sensor is now pervasive in production disk drives. However, the use of spin valves in tape remains noticeably absent. This is predominantly because the media properties and areal densities currently used in tape are considerably different to those in disk. The tape media thickness and thus moment-thickness product (M/sub r//spl delta/) dominates the recording in tape. The large flux levels emanating from the longer wavelength recordings in RLL recording codes drive the recording method (write equalization) and the read head design characteristics. MR sensors in the form of soft adjacent layer (SAL) biased devices and dual stripe (DSMR) structures are presently used in production tape systems, which together with write equalization give high signal amplitudes at short wavelengths with little or no element saturation at long wavelengths. Another difference between tape and disk systems is the multi-channel read-while-write function giving the unwanted parasitic feedthrough (or cross-feed) noise. It is tape specific noise sources such as this that drive the need for more raw signal amplitude off the tape even though the areal density of present and future tape systems does not approach that of current disk systems. The paper compares a 20 /spl mu/m wide DSMR head with a 4 /spl mu/m wide spin valve similar to that used in disk systems for tape applications.