Computation of the lattice dynamics for the low-coverage Au/Cu(111) ordered metallic surface alloy system

Abstract

The lattice dynamics of the ordered Au/Cu(111) surface alloy system are investigated, in particular for the low-coverage ordered Cu(111)-Au 3×3 R30° surface alloy structure. The computations are developed using the phase field matching theory (PFMT) and the Green's functions (GF) formalism. Dispersion branches for surface phonons and resonances along the directions of high symmetry ΓM‾, MK‾, and KΓ‾ of the two-dimensional (2D) surface Brillouin zone (BZ) of the system, are computed. The vibration local densities of states (LDOS) are also determined for representative atomic sites at the surface alloy boundary. The lattice dynamics of the Cu(111)-Au 3×3 R30° surface reveal novel surface phonon and resonance dispersion branches that could be of potential interest for electronic, chemical, and spintronic applications, notably via electron-phonon interactions at this surface.