Shielded MR head for high-density magnetic recording (invited)

Abstract

A narrow-gap shielded magnetoresistive (MR) head with a 8-μm track width has been constructed for high-density magnetic recording. The head consists of a pair of NiFe shields and a trilayered MR element between the shields. In the MR element NiFe, Ti, and amorphous CoZrMo films are used. The thickness of the three layers and the shields, as well as the shield gap length, are optimized with a one-dimensional self-consistent calculation. The shielded MR head has been fabricated using calculated thickness parameters for individual layers: 60 nm for CoZrMo with 40 nm NiFe and 20 nm Ti, 1-μm shields, and 0.5 μm for the total shield gap. The reproduced characteristics from the MR head are evaluated with a plated disk. Neither Barkhausen noise nor distortion is observed in the output waveform. The output voltage is 600 μVpp at a 4 mA/μm sense current with 30 kFCI transition density. The D50 transition density is 40 kFCI. These values are in good agreement with the calculated values. Assuming a 12-μm track pitch, crosstalk is −29 dB from off-track crosstalk characteristics. This shielded MR head has a potential to achieve high recording density with 40 kBPI and 2000 TPI for small-size disk drives.