Micromagnetics of small unshielded MR elements

Abstract

A two-dimensional micromagnetic simulation is carried out for small unshielded magnetoresistive (MR) elements. The response of the magnetization to uniform cycling of a transverse external field is studied. For an isolated element without any bias field, the magnetic response is hysteretic, resulting in noisy MR output. For longitudinal patterned exchange bias, the pinning width has to exceed a critical value to achieve a noise-free response. Increasing the edge biasing angle beyond 45° induces undesirable multidomain activities. Soft adjacent layer (SAL) biasing is investigated by using a dual-layer model. Various exchange biasing schemes of the end regions of the MR and SAL layers have been numerically implemented, and it is seen that symmetric exchange coupling of the edge regions of both layers yields a desirable MR response.