Ren Wiscons, Roy/Nuckolls Groups
4:00pm - 5:00pm
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Layered van der Waals (vdW) materials displaying in-plane anisotropy are of fundamental and practical interest due to their ability to directionally transport charge, spin, and/or energy as a result of broken symmetry in their electronic and magnetic structures. In-plane conductivity anisotropy is generally low, between 130 and 180%, and uncommon in low band gap semiconductors, semimetals, and metals because it is challenging to access structure types that lead to dramatic enough differences in electronic coupling along different conduction pathways that transport anisotropy can be realized experimentally. TaIrTe4 is a unique example that displays an impressive 220% in-plane conductivity anisotropy due to alternating stripes of metallic TaTe2 and semimetallic IrTe2 present in each layer of the material. This presentation describes the discovery of two new anisotropic vdW materials with in-plane structures identical to TaIrTe4, a-TaFeTe4 and b-TaFeTe4. We find that a-TaFeTe4 shows up to 250% in-plane anisotropy, outcompeting TaIrTe4, which is reported as having the strongest in-plane conductivity anisotropy among materials with comparable carrier densities. We also explore the possibility that broken inversion symmetry in b-TaFeTe4 produces Weyl points in the electronic band structure. Eight Weyl nodes within 50 meV of the Fermi energy are computationally predicted for b-TaFeTe4, indicating that they likely contribute to transport in this polytype.
Friday, September 25, 2020 at 4:00pm
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