Electronically enhanced layer buckling and Au-Au dimerization in epitaxial LaAuSb films

Journal Article · 06 February 2019 · Physical Review Materials

DOI: https://doi.org/10.1103/PhysRevMaterials.3.024201 · OSTI ID:1496062

Strohbeen, Patrick J. ^[1]; Du, Dongxue ^[1]; Zhang, Chenyu ^[1]; Shourov, Estiaque H. ^[1]; Rodolakis, Fanny ^[2]; McChesney, Jessica L. ^[2]; Voyles, Paul M. ^[1]; Kawasaki, Jason K. ^[1]

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1. Univ. of Wisconsin Madison, Madison, WI (United States)
2. Argonne National Lab. (ANL), Argonne, IL (United States)

Here, we report the molecular beam epitaxial growth, structure, and electronic measurements of single-crystalline LaAuSb films on Al₂O₃ (0001) substrates. LaAuSb belongs to a broad family of hexagonal ABC intermetallics in which the magnitude and sign of layer buckling have strong effects on properties, e.g., predicted hyperferroelecticity, polar metallicity, and Weyl and Dirac states. Scanning transmission electron microscopy reveals highly buckled planes of Au-Sb atoms, with strong interlayer Au-Au interactions and a doubling of the unit cell. This buckling is four times larger than the buckling observed in other ABCs with similar composition, e.g., LaAuGe and LaPtSb. Photoemission spectroscopy measurements and comparison with theory suggest an electronic driving force for the Au-Au dimerization, since LaAuSb, with a 19-electron count, has one more valence electron per formula unit than most stable ABCs. Our results suggest that the electron count, in addition to conventional parameters such as epitaxial strain and chemical pressure, provides a powerful means for tuning the layer buckling in ferroic ABCs.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States); Univ. of Wisconsin, Madison, WI (United States)
• Sponsoring Organization: Army Research Office; National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); University of Wisconsin - Madison - Materials Research Science and Engineering Center (MRSEC)
• Grant/Contract Number: AC02-06CH11357; FG02-08ER46547
• OSTI ID: 1496062
• Journal Information: Physical Review Materials, Journal Name: Physical Review Materials Journal Issue: 2 Vol. 3; ISSN PRMHAR; ISSN 2475-9953
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English