MS26-01 - Some recent Advances in the Surface Science of Complex Metallic Alloys


Ronan McGrath (University of Liverpool, United Kingdom)

Complex metallic alloys present unique challenges and opportunities in surface science, both for preparation of clean surfaces and for epitaxial studies.

Studies of three Ag-In-RE(100) (RE=Yb,Gd,Tb) approximants illustrate a variety of surface behaviours when prepared in ultra-high-vacuum conditions [1] from flat surfaces to multiple faceting; I will discuss the origin these behaviours in terms of surface atomic bonding.

In recent work, we demonstrated that C60 molecules adsorbed on this surface at room temperature form a Fibonacci square grid – the first physical manifestation of a prediction made in 2002 by Lifshitz [2]. In this case the C60 molecules bond preferentially to Mn atoms in the surface layer, which are arranged in the Fibonacci square grid geometry [2].

In a further study, the adsorption of Pb atoms on the 3-fold surface of the icosahedral Ag-In-Yb quasicrystal proceeds in an unusual way; instead of layer-by-layer growth as was observed on the five-fold surface [3], the atoms form quasicrystalline Pb nanoclusters by mimicking the structure of the underlying substrate. I will discuss whether this is long-sought evidence for "cluster stability" in quasicrystals.

1. S. Hars, H. R. Sharma, J. A. Smerdon, T. P. Yadav, A. Al-Mahboob, J. Ledieu, V. Fournée, R. Tamura, and R. McGrath, Phys. Rev. B 93 (2016) 205428
2. S. Coates, J.A. Smerdon, R. McGrath & H. R. Sharma, Nature Communications  9 (2018) 3435.
3. S. Coates, S. Thorn, R. McGrath and H.R. Sharma, in preparation