Surface structures of complex intermetallic compounds: An ab initio DFT study for the (100) surface of o-Al(13)Co(4)

Autor(en)

Marian Krajci, Juergen Hafner

Abstrakt

The formation and the structural and electronic properties of the (100) surface of the complex intermetallic compound Al(13)Co(4) have been investigated using ab initio density functional methods. While the layered crystal structure of the compound suggests that the (100) surface is formed by cleaving the crystal between adjacent flat (F) and puckered (P) layers, a simulated cleavage experiment shows that the P layer splits into two complementary parts to preserve the integrity of very stable clusters forming pentagonal bipyramids (PB's). The stable surface is terminated by an incomplete P layer consisting of the tips of the PB clusters and exposing in the interstices that part of the underlying F layer forming the connection between the PB's. The stability of this strongly corrugated surface is further confirmed by the calculation of the surface energies and of the formation energies of surface vacancies, as well as by a simulated high-temperature annealing. The analysis of the electronic structure shows that the stability of the PB clusters arises primarily from strong, partially covalent vertical Co-Al-Co bonds between the tips of the clusters. Simulated scanning tunneling microscopy (STM) images are provided to permit a comparison with the STM experiments of Addou et al. [Phys. Rev. B 80, 014203 (2009)]. Measured and simulated STM images are in good agreement, possible reasons for the remaining differences in the Al/Co contrast are discussed in detail.

Organisation(en)

Computergestützte Materialphysik

Externe Organisation(en)

Slovenian Academy of Sciences and Arts

Journal

Physical Review B

Band

84

Anzahl der Seiten

14

ISSN

1098-0121

DOI

https://doi.org/10.1103/PhysRevB.84.115410

Publikationsdatum

09-2011

Peer-reviewed

Ja

ÖFOS 2012

103009 Festkörperphysik, 103015 Kondensierte Materie, 103025 Quantenmechanik, 103036 Theoretische Physik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/7a0fec6d-bf29-4e84-a6c6-9d53601fb95d