Reading and writing of vortex circulation in pseudo-spin-valve ring devices

Abstract

The authors present a simple method of reading the circulation direction of vortex states in pseudo-spin-valve ferromagnetic ring devices via magnetoresistance measurements. It is shown that by placing the current contacts asymmetrically onto the structure, the circulation of a vortex state in the hard layer may be read directly from the total resistance of the device. Furthermore, they show that by choosing the direction in which the ring is initially saturated prior to obtaining the vortex state, the vortex circulation may be selectively written to the structure, creating the basis of a working memory element.