Influence of substrate roughness on spin reorientation transition of ultrathin Co films on Pd(111)

Abstract

We report a drastically different behavior in spin reorientation transition of ultrathin Co films grown on smooth versus rough Pd(111) single crystal substrates. The morphology and magnetic anisotropy of epitaxially grown Co films have been studied with in situ scanning tunneling microscopy (STM) and surface magneto-optical Kerr effects. On an atomically flat substrate, a smooth transition from perpendicular to in-plane magnetization occurs in a thickness interval of over 1.5 ML, beginning at similar to4.5 ML. In contrast, rough substrate causes the transition to begin quite earlier at less than or equal to3 ML and complete abruptly in less than 1 ML range. Morphology difference of the Co films obtained with STM suggests that on rough substrate, nonuniform coverage of Co leads to locally thicker regions triggering earlier spin reorientation transition. (C) 2001 American Institute of Physics.