Interface morphology of a Cr(001)/Fe(001) superlattice determined by scanning tunneling microscopy and x-ray diffraction: A comparison

A Cr(001)/Fe(001) superlattice with ten bilayers grown by molecular beam ep itaxy on a Ag(001) substrate is studied by in situ scanning tunneling micro scopy (STM) and ex situ x-ray diffraction (XRD). Layer-resolved roughness p arameters determined from STM images taken in various stages of the superla ttice fabrication are compared with average values reported in the literatu re or obtained from the fits of our XRD data. Good agreement is found for t he rms roughnesses describing vertical roughness and for the lateral correl ation lengths characterizing correlated as well as uncorrelated interface r oughness if peculiarities of STM and XRD are taken into account. We discuss in detail (i) the possible differences between the STM topography of a fre e surface and the morphology of a subsequently formed interface, (ii) contr ibutions due to chemical intermixing at the interfaces, (iii) the compariso n of XRD parameters averaged over all interfaces versus layer-resolved STM parameters, and (iv) the question of the coherent field of view for the det ermination of rms values. (C) 2001 American Institute of Physics.