A hundred years ago, Heinrich Barkhausen heard the crackling sounds produced by magnetic domains expanding and contracting in an iron bar. Those clicks were the first experimental evidence of the jumpy processes associated with the displacements of the domain walls. The movements determine many of the useful properties of ferromagnets, including how readily they respond to an applied magnetic field in transformers and electric motors.
But controlling domain propagation is difficult. Microscopic magnetization processes are stochastic, and disorder is inevitably present. In this Quick Study, we discuss how domain walls can nevertheless be manipulated by an electric current in order to move, store, and process digital information encoded in their magnetizations.
Early proposals for manipulating magnetic domains date back to the 1960s. Memory devices based on the propagation of cylindrical domains, or bubbles, in perpendicularly magnetized thin films reached a remarkable level of circuit integration and speed for their time....
