Electric current driven polarity change of nanomgnets

Abstract

This paper investigates the initial steps in setting logical inputs to an edge-driven computational device composed of an array of magnetic nickel dots. An edge driven device computes by setting inputs on one edge of the device, driving the entire system into a global ground state, and reading the results on the far edge. In the proposed architecture, the device is made up of an array of nickel dots and offers low power dissipation, high integration density, room temperature operation and simple fabrication steps. Current traveling down a nearby wire is used to set the magnetic polarity of dots on the input edge. The logical state of a dot is identified with the orientation of the dots magnetic field. The switching of polarity was attempted via a locally induced magnetic field generated by reversing the direction of the current in the nearby wire, a first step in the ultimate construction of an edge-driven device. The aluminum wire had dimensions of 250 nm in thickness, 8 μm in width, and 40 μm in length. The nickel dots, formed by electron beam lithography, had a thickness of 100 nm and diameter ranging from 300 nm to 500 nm. Switching of the magnetic polarity of dots near the wire was observed using magnetic force microscopy (MFM), with MFM cantilever phase images used to identify the reversals. In contrast, dots further away from the wire did not appear to be influenced by the direction of current in the wire, another requirement for edge-driven devices.