Raman Signatures of Broken Inversion Symmetry and In‐Plane Anisotropy in Type‐II Weyl Semimetal Candidate TaIrTe₄

The layered ternary compound TaIrTe 4 is an important candidate to host the recently predicted type‐II Weyl fermions. However, a direct and definitive proof of the absence of inversion symmetry in this material, a prerequisite for the existence of Weyl Fermions, has so far remained evasive. Herein, an unambiguous identification of the broken inversion symmetry in TaIrTe 4 is established using angle‐resolved polarized Raman spectroscopy. Combining with high‐resolution transmission electron microscopy, an efficient and nondestructive recipe to determine the exact crystallographic orientation of TaIrTe 4 crystals is demonstrated. Such technique could be extended to the fast identification and characterization of other type‐II Weyl fermions candidates. A surprisingly strong in‐plane electrical anisotropy in TaIrTe 4 thin flakes is also revealed, up to 200% at 10 K, which is the strongest known electrical anisotropy for materials with comparable carrier density, notably in such good metals as copper and silver.