Yoke type magnetoresistive heads with suppressed Barkhausen noise

Thin film heads using magnetoresistive effect will generate noticeable Barkhausen noise attributable to the domain wall activity in the magnetoresistive (MR) elements as the tracks are narrower. Dependence of the Barkhausen noise occurrence on the shape of MR elements was studied. Here we paid attention to the flux closure scheme in which an MR element is shaped into a "picture frame" geometry called Closed Type MR element (CTMR element) with a small gap, since the MR element of such configuration was not likely to be limited by the track pitch and width requirements when built in the multitrack head construction. MR characteristics at various small points of the CTMR element were measured using a Kerr-effect microscope to verify the Barkhausen noise suppression effect of the element. Then, 18-track yoke type MR heads with CTMR elements or conventional stripe MR elements were fabricated and compared for the reproducing characteristics. The comparison revealed that both noise level and higher harmonic distortion were about 10dB lower with CTMR elements than with stripe MR elements.