Surface reconstructions are generally observed on covalently bonded materials, and they are not frequent on metal surfaces. Recently, quantum calculations on the Al2Cu metallic alloy identified covalent-like Al-Al bonds . In this study, we show that these covalent bondings are at the origin of a surface reconstruction for Al2Cu(001) . The bulk structure of the Al2Cu intermetallic compound is described by graphite-like Al 63 nets . The combination of both experimental methods (STM, STS, LEED, UPS, XPS) and ab-initio computational methods (atomic relaxations, STM simulations, electronic structure calculations) gives many arguments to match the surface plane with a bulk truncated surface model terminated by incomplete Al planes. The covalent-like interaction is highlighted by ab-initio calculations: the energetic cost associated with the removal of pairs of Al atoms is the lowest for the two nearest surface Al atoms.
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