Magnetic switching in cobalt films by adsorption of copper

Abstract

MAGNETIC storage of information requires the ability to manipulate the magnetization of thin films with high sensitivity and spatial resolution. Non-magnetic overlayers are known to affect the characteristics of magnetic films: for example, the direction of magnetization of cobalt and iron films can be altered by deposition of a monolayer of copper and gold, respectively1–3. The magnetic properties of cobalt films seem to be particularly sensitive to copper overlayers—deposition of only sub-monolayer amounts of copper will decrease the coercive field required to invert the magnetization direction4. Here we show that copper coverages as small as three-hundredths of a monolayer are sufficient to rotate by 90° the magnetization of Co films up to 20 atomic layers thick. This implies that the spins of about 500 cobalt atoms switch direction for each copper atom added. Adding more copper eventually switches the magnetization back to its original direction. This fine tuning of thin-film magnetism might be useful for developing sensitive magnetic-field sensors, as well as for magnetic recording. © 1995 Nature Publishing Group.