Unshielded Mr Elements with Patterned Exchange-Biasing

Abstract

In this work, we discuss the concept of patterned longitudinal-biasing as a means to suppress Barkhausen noise in narrow-track M R elements. This scheme has the advantage that the performance of the read-region is relatively insensitive to the exact magnitude of the externally applied longitudinal-bias, as long as this bias is large enough to ensure good longitudinal alignment of magnetization at the tail-regions. In particular, large longitudinal-bias can be applied at the tail-regions without serious permeability reduction in the center read-region. We demonstrate this concept in the experimental fabrication and testing of unshielded permalloy MR elements with patterned exchange-biasing. Results show that these elements do indeed exhibit quiet and stable responses, but without the severe sensitivity reduction which is characteristic of MR elements under strong uniform longitudinal-biasing. © 1989 IEEE