Intrinsic Negative Magnetoresistance and Broadband Photoresponse in Magnetic van der Waals Crystal TaFeTe ₂

ABSTRACT 2D van der Waals (vdW) materials with broken symmetry, such as MM′Te ₂ (where M═Nb, Ta, and M′ = Fe, Co, Ni), have attracted considerable research interest due to their unique magnetic structures and optical‐phonon‐induced phase transitions, providing a versatile platform for discovering novel physical phenomena. Here, we report the synthesis of TaFeTe ₂ single crystals that can be mechanically exfoliated to the 2D limit. The as‐grown crystals display characteristic spin‐glass behavior and intrinsic unsaturated negative magnetoresistance up to 9 T, likely arising from the orbital effect associated with variable‐range hopping transport and/or magnetic disordering. Notably, TaFeTe ₂ ‐based photodetectors exhibit robust photocurrent responses in the sample's interior under self‐powered conditions, primarily arising from an additional charge separation mechanism induced by the optical‐phonon‐triggered non‐centrosymmetric phase. Under standard bias, the detectors achieve a high responsivity of 0.18 A W ⁻¹ and broadband photoresponse spanning the visible to mid‐infrared spectrum. These features highlight the material's strong potential for advanced multifunctional optoelectronic applications.