Self-initialization of short magnetoresistive sensors into a single

Abstract

A a dual element magnetoresistive sensor that uses the longitudinal field produced by the sense/bias currents to initialize the elements into a stable antiparallel state. The dual element magnetoresistive sensor comprises two magnetoresistive elements having first and second conductors coupled thereto. The first and second conductors are oriented in the same direction as the magnetoresistive elements in their contact areas. A third conductor is disposed between and coupled to the two magnetoresistive elements at their opposite ends. The third conductor is oriented transverse to the directions of the first and second sensor elements, and is adapted to conduct current therethrough in a direction transverse to the currents conducted by the first and second conductors. Currents conducted by all three conductors self-initialize the magnetoresistive elements into a single domain state. Also, the current flowing in the third conductor creates an anti-parallel longitudinal field in the two sensor elements that is oriented in the same direction as closure fields present in the magnetoresistive elements. These fields ensure that a single domain state is produced in the magnetoresistive elements. An alternative design for the third conductor employs one conductor portion that provides a current distribution that initializes the sensor. This current distribution initializes the sensor. Another conductor portion is used during reading and provides a current distribution that is similar to the distribution produced by the first and second conductors. This ensures that the across-the-track response is symmetric. A small fraction of the sense current flows in the initializing conductor portion to provide stabilization during reading.