Local strain induced structural inhomogeneity in Fe thin films on Cu(001)

Abstract

We investigate atomic-scale surface structures of 7 monolayer Fe thin films on a Cu(001) substrate by scanning tunneling microscopy. Near the step edges, the epitaxial fcc(001) lattice is stabilized on the upper terrace. In contrast, on the lower terrace, the bulk stable bcc(110) lattice and several surface reconstructions with high-density adsorbates are observed. The changes of electronic structures on the latter region from fcc Fe to bcc Fe is verified by spectroscopic measurements after the desorption of adsorbates, suggesting the local strain effect as the dominant origin of observed structural inhomogeneity.