The measurement of Barkhausen noise in magnetoresistive elements using the magnetoresistive susceptibility method

A novel magnetoresistive susceptibility technique for studying Barkhausen noise in magnetoresistive (MR) elements is reported. Phase-sensitive detection has been used to detect the response of MR elements to anapplied uniform ac sinusoidal field, the experimental conditions approximating those of the head in actual operation. Quantitative information on the noise, as well as the positions of the Barkhausen jumps on the MR response curves has been obtained. Conditions for noiseless operation of MR elements have been defined, and depend on the ac signal field amplitude and the magnitude of a secondary external easy axis field. Theoretical prediction of the Barkhausen noise-free MR response characteristics show good agreement with experiment.