Chiral surfaces and metal/ceramic heteroepitaxy in the Pt/SrTiO 3(621) system

Abstract

Low-energy electron diffraction (LEED), atomic force microscopy (AFM), and X-ray diffraction (XRD) have been used to investigate the structural and morphological character of a naturally chiral ceramic SrTiO 3(621) substrate and of Pt and Cu thin films deposited on its surface. AFM experiments showed that as-received chirally-oriented SrTiO 3(621) substrates display atomically smooth surface morphologies, while LEED patterns revealed that the surface structure has a net chirality. Pt(621) and Cu(621) thin films were grown heteroepitaxially on SrTiO 3(621) substrates, as confirmed by XRD. AFM showed that the film surfaces were atomically smooth and LEED illustrated that the Pt films exhibit surface chirality, and by implication that the atomically-flat chirally-oriented Cu films also have chiral surfaces. The characteristics of the observed LEED patterns, where splitting of diffraction spots is considered to arise from the kinked step features of naturally chiral fcc metal surfaces, are discussed with respect to existing models. These results indicate that the chiral SrTiO 3(621) ceramic surface drives the growth of single-enantiomer, chiral, metal (621) thin films.