“…STM images can also be explained as bulk atomic planes. The observation of two-fold symmetry of the surface is in agreement with previous STM results 20 , 21 (Supplementary Note 2 ). Fig.…”
Quasicrystals differ from conventional crystals and amorphous materials in that they possess long-range order without periodicity. They exhibit orders of rotational symmetry which are forbidden in periodic crystals, such as five-, ten-, and twelve-fold, and their structures can be described with complex aperiodic tilings such as Penrose tilings and Stampfli–Gaehler tilings. Previous theoretical work explored the structure and properties of a hypothetical four-fold symmetric quasicrystal—the so-called Fibonacci square grid. Here, we show an experimental realisation of the Fibonacci square grid structure in a molecular overlayer. Scanning tunnelling microscopy reveals that fullerenes (C60) deposited on the two-fold surface of an icosahedral Al–Pd–Mn quasicrystal selectively adsorb atop Mn atoms, forming a Fibonacci square grid. The site-specific adsorption behaviour offers the potential to generate relatively simple quasicrystalline overlayer structures with tunable physical properties and demonstrates the use of molecules as a surface chemical probe to identify atomic species on similar metallic alloy surfaces.
“…STM images can also be explained as bulk atomic planes. The observation of two-fold symmetry of the surface is in agreement with previous STM results 20 , 21 (Supplementary Note 2 ). Fig.…”
Quasicrystals differ from conventional crystals and amorphous materials in that they possess long-range order without periodicity. They exhibit orders of rotational symmetry which are forbidden in periodic crystals, such as five-, ten-, and twelve-fold, and their structures can be described with complex aperiodic tilings such as Penrose tilings and Stampfli–Gaehler tilings. Previous theoretical work explored the structure and properties of a hypothetical four-fold symmetric quasicrystal—the so-called Fibonacci square grid. Here, we show an experimental realisation of the Fibonacci square grid structure in a molecular overlayer. Scanning tunnelling microscopy reveals that fullerenes (C60) deposited on the two-fold surface of an icosahedral Al–Pd–Mn quasicrystal selectively adsorb atop Mn atoms, forming a Fibonacci square grid. The site-specific adsorption behaviour offers the potential to generate relatively simple quasicrystalline overlayer structures with tunable physical properties and demonstrates the use of molecules as a surface chemical probe to identify atomic species on similar metallic alloy surfaces.
“…Some terraces can reach micrometers in size. The terraces are much larger than in the twofold i-Al-Pd-Mn surface [20,21]. Consistently with LEED patterns, no indication of facets is observed by STM.…”
Section: Step-terrace Structuresupporting
confidence: 82%
“…In agreement with the twofold symmetry, rectangle shaped terraces with straight step-edges are frequently observed. Similar rectangle shaped terraces are present on the twofold surface of i-Al-Pd-Mn [21,22]. On the basis of the analysis of fast Fourier transform (FFT) patterns of STM images, we identify the crystallographic direction of the step-edges along the twofold axes.…”
The structure of the twofold surface of the icosahedral (i-)Ag-In-Yb quasicrystal has been investigated using low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). The LEED confirms that the surface exhibits quasicrystalline long range order with the twofold rotational symmetry expected from the bulk. STM images reveal a step-terrace structure with terrace size comparable to that of the other high symmetry surfaces of the same quasicrystal. The distribution of step heights and high resolution STM images of terraces suggest that the surface terminates at bulk planes that intersect the center of rhombic triacontahedral clusters, the building blocks of the system, as in the case of the threefold and fivefold surfaces of the system. These planes are rich in Yb and In. No facets are observed on the surface, suggesting that the twofold surface is as stable as the other high symmetry surfaces.
“…Among the different attempts to achieve pseudomorphic growth, the adsorption of Cu atoms has led to the formation of surface alloys on different systems. It has been shown using STM and LEED techniques that Cu adatoms deposited on the fivefold and twofold i -AlPdMn surface yields quasiperiodic structures [86, 87]. However, five-rotational domains of (110)-orientated β -Al(Cu, Fe) phase are obtained for 8 ML Cu atoms adsorbed on the fivefold i -Al-Cu-Fe surface [88].…”
Section: Thin Films Alloy Surfaces and Reactivity Of Cma Surfacesmentioning
We present a review on recent work performed on periodic complex metallic alloy (CMA) surfaces. The electronic and crystallographic structures of clean pseudo-tenfold, pseudo-twofold, sixfold surfaces will be presented along with the recent findings on CMA of lower structural complexity, i.e. with a smaller unit cell. The use of CMA surfaces as templates for thin film growth and the formation of surface alloy will also be introduced. The reactivity of these complex surfaces and their impact in the field of heterogeneous catalysis will be discussed. Finally, common trends among these systems will be highlighted when possible and future challenges will be examined.
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