High electrical conductivity in the epitaxial polar metals LaAuGe and LaPtSb
Abstract
Polar metals are an intriguing class of materials that simultaneously host free carriers and polar structural distortions. Despite the name “polar metal,” however, most well-studied polar metals are poor electrical conductors. Here, we demonstrate the molecular beam epitaxial growth of LaPtSb and LaAuGe, two polar metal compounds whose electrical resistivity is an order of magnitude lower than the well studied oxide polar metals. These materials belong to a broad family of ABC intermetallics adopting the stuffed wurtzite structure, also known as hexagonal Heusler compounds. Scanning transmission electron microscopy reveals a polar structure with unidirectionally buckled BC (PtSb and AuGe) planes. Magnetotransport measurements demonstrate good metallic behavior with low residual resistivity (ρLaAuGe = 59.05 μΩ cm and ρLaAPtSb = 27.81 μΩ cm at 2 K) and high carrier density (nh ∼ 1021 cm−3). Photoemission spectroscopy measurements confirm the band metallicity and are in quantitative agreement with density functional theory (DFT) calculations. Through DFT-chemical pressure and crystal orbital Hamilton population analyses, the atomic packing factor is found to support the polar buckling of the structure although the degree of direct interlayer B–C bonding is limited by repulsion at the A–C contacts. When combined with predicted ferroelectric hexagonal Heuslers, these materials provide a new platform for fully epitaxial, multiferroic heterostructures.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Dec 01, 2019
- Source ID
- 10.1063/1.5132339
Entities
People
- Amber Lim
- Chenyu Zhang
- Daniel C Fredrickson
- Dongxue Du
- Estiaque H. Shourov
- Fanny Rodolakis
- Jason K Kawasaki
- Jessica L McChesney
- Patrick J. Strohbeen
- Paul M. Voyles
Organizations
- Argonne National Laboratory
- Army Research Office
- National Science Foundation
- United States Department of Energy
- University of Wisconsin–Madison