Structural and electronic properties of thin Co films on Fe(001) and Fe(001)-p(1 x 1)O in the bct-to-hcp transition regime

We present a combined study of structural and electronic properties of thin Co films (up to 50 ML) grown on Fe(001). By means of primary-beam diffract ion modulated electron emission, we found a structural transition between a strained bce structure (bct) and the stable hcp phase occurring at similar to 15 ML Co coverage. This structural change has a counterpart in the unoc cupied electron states of the Co overlayer, as seen by absorbed current spe ctroscopy. We demonstrate that the evolution of AC spectra can be used to m onitor the mentioned transition and apply this technique to the case of Co grown on Fe(001)-p(1 x 1)O. It is found that the presence of the oxygen cau ses a delayed onset of the bct-hcp transition. (C) 2000 Elsevier Science B. V. All rights reserved.