Growth and magnetic properties of ultrathin Co films on Pd(111) investigated by UHV in situ SMOKE and STM

Abstract

Growth and magnetic properties of Co ultrathin films on Pd(111) surface are studied with a ultrahigh vacuum scanning tunneling microscope (STM) and in situ surface magneto-optical Kerr effect measurement as a function of Co thickness. STM images of Co-covered surface reveal that the growth proceeds as a good layer-by-layer epitaxy up to a thickness of 2 ML. Image at a coverage of 1 ML shows almost complete monolayer coverage instead of disconnected islands. At higher coverages, the surface shows uniformly distributed three-dimensional (3D) clusters of similar to5 nm size manifesting 3D-like growth mode. Co films begin to show ferromagnetism at a coverage of 1.5 ML with a strong perpendicular magnetic anisotropy, which persists up to 5 ML. For the Co films thicker than 5 ML, reorientation transition from perpendicular to in-plane magnetic anisotropy is observed to occur over a thickness range of similar to1.5 ML. Interestingly, in this thickness range, Pd overlayer is found to drastically change the magnetic behavior. (C) 2001 American Institute of Physics.