One-Dimensional Periodic Buckling at a Symmetry-Incompatible Heterointerface of the NaCl(001) Monolayer on Ir(111)

Abstract

Monolayer and multilayer NaCl(001) films are grown on an Ir(111) substrate, and strain relaxation modes are investigated by scanning tunneling microscopy (STM) and density functional theory calculations. We report that monolayer NaCl(001) exhibits an apparent one-dimensional periodic buckling along the [010] direction, which separates one-dimensional domains of pristine lattices. An atomic model of the monolayer NaCl(001)-(2 × 6) lattice on an Ir(111)-(4 × 73) substrate is proposed, and related simulation reproduces all the STM features. The calculations suggest that the 4–6 symmetry incompatibility of the NaCl(001)/Ir(111) interface leads to the formation of domain boundaries with alternately arranged top-sited and bridge-sited adatom lines along [100], resulting in one-dimensional atomic buckling. We also observe that the atomic buckling is veiled as the NaCl(001) increases to bilayer and above, suggesting that this relaxation mode is finely tuned by the crystal thickness.