Magnetoresistance of submicrometre multilayer Wheatstone bridges as a probe of magnetic reversal mechanism

The magnetoresistance of elliptical NiFe/Cu/Co multilayer rings with deep submicrometre widths contacted in a Wheatstone bridge configuration has been characterized. The rings show large voltage signals corresponding to magnetic configurations in which either the Co or the NiFe layer is in a vortex state. This result indicates that asymmetrically placed 360 deg. domain walls can be present in the vortex states attained during the reversal of the magnetic layers. Minor loop cycling generates a range of possible remanent resistance levels in the rings, which makes these devices interesting candidates for multiple-bit-per-cell magnetic random access memory or for non-volatile programmable logic devices. (fast track communication)