Labyrinthine Island Growth during Pd/Ru(0001) Heteroepitaxy

TL;DR

This study reveals a novel labyrinthine growth mode of Pd islands on Ru(0001), driven by surface alloy formation that influences step attachment rates, observed through advanced microscopy and theoretical modeling.

Contribution

It introduces a new epitaxial growth mode characterized by labyrinthine patterns caused by surface alloy effects, combining experimental and theoretical approaches.

Findings

Labyrinthine island patterns observed during Pd/Ru(0001) growth.

Surface alloy formation reduces step attachment rates.

Growth instability favors fast-advancing step sections.

Abstract

Using low energy electron microscopy we observe that Pd deposited on Ru only attaches to small sections of the atomic step edges surrounding Pd islands. This causes a novel epitaxial growth mode in which islands advance in a snakelike motion, giving rise to labyrinthine patterns. Based on density functional theory together with scanning tunneling microscopy and low energy electron microscopy we propose that this growth mode is caused by a surface alloy forming around growing islands. This alloy gradually reduces step attachment rates, resulting in an instability that favors adatom attachment at fast advancing step sections.