Narrow track dual magnetoresistive heads for tape

An experimental investigation of a dual magnetoresistive head tested on a Metrum tape test stand, is presented. The dual magnetoresistive (DMR) head has a trackwidth of 4 μm and a gap length of 0.1 μm. Metal particle tape, with a Mrδ of 16 memu/cm2 and a coercivity of 1.8 kOe, was used. A square wave was recorded with an FeAlN thin film inductive head, with a trackwidth of 33 μm and a gap of 1.9 μm. A shielded shunt biased MR head used in quarter inch cartridge drives (QIC), with a trackwidth of 19 μm and a shield to element gap of 0.25 μm was used as a benchmark. The DMR head showed a larger signal to dc erased noise per unit trackwidth than the QIC MR head, at linear densities of 20 to 100 kfci. Isolated transitions and dibits with a bit spacing of 0.3 μm were recorded for time domain measurements. The dibit response of the DMR head, characterized by a unipolar pulse with small side over/undershoots demonstrated the differential character of the DMR head. The QIC MR head PW50, measured directly from the isolated transition response and indirectly from the dibit response, was 1.4 μm. This large PW50 value was essentially write process limited, to first order independent of the read head gap length.