TaRhTe₄ (Tantalum Rhodium Telluride)

 TaRhTe₄ (Tantalum Rhodium Telluride) — Introduction
TaRhTe₄ is a ternary transition-metal telluride composed of tantalum (Ta), rhodium (Rh), and tellurium (Te). It crystallizes in a low-symmetry orthorhombic structure and has been identified as a candidate type-II Weyl semimetal. Compared with its isostructural counterpart TaIrTe₄, TaRhTe₄ is considered closer to the “ideal” Weyl semimetal phase. Its exotic topological electronic states, strong spin–orbit coupling, and highly anisotropic transport properties make it a promising material for both fundamental condensed-matter physics and next-generation quantum devices.
 Physical Properties
Appearance: Metallic, silver-gray to dark crystalline solid.
Crystal Structure: Orthorhombic, non-centrosymmetric structure (space group Pmn2₁). The lattice exhibits a layered arrangement with weak interlayer bonding, giving rise to pronounced anisotropy.
Electronic Properties:
Hosts tilted type-II Weyl cones near the Fermi level.
No conventional semiconductor band gap — instead, Weyl nodes with linear dispersion dominate the electronic spectrum.
Band Gap: Effectively zero band gap (semimetallic); topological Weyl states replace conventional band-edge states.
Transport Properties: Negative longitudinal magnetoresistance, strong anisotropy in conductivity, and nonlinear Hall effects have been observed.
Optical Properties: Exhibits nonlinear optical responses such as second harmonic generation and photocurrent effects due to strong SOC and topological band structure.
Exfoliation: Although the structure is layered, exfoliation into stable monolayers is more difficult than typical van der Waals semiconductors (e.g., MoS₂, CrI₃). Few-layer flakes may be achievable, but bulk or thick crystals are more commonly studied.
 Applications
Topological Electronics
Provides a platform for designing low-dissipation interconnects, topological quantum devices, and quantum sensors.
Spintronics
Weyl fermion states and Berry curvature effects enable efficient spin–charge interconversion, making TaRhTe₄ attractive for spintronic devices.
Quantum Transport Research
Serves as an excellent model system for studying chiral anomaly, nonlinear Hall effect, and topological magnetoresistance.
Optoelectronics and Nonlinear Optics
Anisotropic optical responses and topological band structure open opportunities for nonlinear photodetectors, polarization-sensitive devices, and quantum photonic applications.