In situ scanning tunneling microscopy observation of surface evolution in magnetically coupled Co/Cu multilayers

Abstract

A series of bilayers of the form Cu(100)/[Co(21 Å)/Cu(21 Å)]n were grown by both ion beam and DC magnetron sputtering techniques. Scanning tunneling microscopy images of the developing layers demonstrate a marked difference in the way in which roughness evolves through the films. The higher energy ion beam sputtered systems show a nonconformal roughness that is characterized by comparatively large lateral length scales. The less energetic magnetron-formed systems exhibit an island-upon-island growth that is conformal from layer to layer. Kerr effect measurements show that the former is ferromagnetically coupled and the latter is antiferromagnetically coupled. An explanation is presented that attributes the differences in roughness to the potential barriers at step edges. Adatom mobility and incident energy are shown to be the determining factors for this kind of conformal growth. © 1996 American Institute of Physics.