Improved Bias and Stability in Dual-Exchange-Biased Unshielded Magnetoresistive Heads

Data is presented for dual-exchange-biased NiFe-TbCo UMR tape heads with improved signal response and process stability. It was found that a Si3N4 passivation layer offered better stability of the exchange bias through head processing than SiO2. In order to improved sensor sensitivity, the longitudinal component of the exchange bias was reduced by increasing the exchange angle to 75° from the sense current direction. This resulted in a +6 dB improvement in signal over previous heads without sacrificing Barkhausen-noise free operation in narrow trackwidths. © 1990 IEEE