Analysis of thermal noise spike cancellation

Thermally induced voltage pulses have been reported by Gorter et al. in the output of magnetoresistive reading heads. To reduce this thermal noise, Gorter et al.1 added a second magnetoresistive element on the same substrate but with a large head-to-tape distance. The outputs of these two stripes are differentially amplified to reject common mode noise. A theoretical analysis is made of the heat flow in magnetoresistive heads due to frictional heat generated at the head/tape interface. This model predicts that the dual stripe geometry will be effective for thermal noise cancellation only for low tape velocity or low thermal noise frequency and/or high thermal diffusivity substrate/cover material for the magnetoresistive elements. This result is also expected to be qualitatively valid for thermal noise due to intermittent cooling by the tape of Joule heat generated in the magnetoresistive elements. © 1975, IEEE. All rights reserved.