Zintl phases are a class of intermetallic materials that have simultaneously ionic and covalent bonding resulting from charge transfer between two different atomic species. We present a combined first principles and experimental study of Zintl-phase SrAl${}_4$, which is grown in thin film form on the perovskite oxide LaAlO${}_3$ using molecular beam epitaxy. The structural properties are investigated using reflection-high-energy electron diffraction, x-ray diffraction, and cross-section transmission electron microscopy, which reveal relaxed epitaxial island growth. Photoelectron spectroscopy measurements verify the Zintl-Klemm nature of the bonding in the material and are utilized to determine the band offset and the work function of SrAl${}_4$, while transport measurements confirm its metallic behavior. The experimentally observed properties are confirmed using density functional calculations.

• Received 11 December 2012

DOI:https://doi.org/10.1103/PhysRevB.88.045314