Intrinsic Negative Magnetoresistance and Broadband Photoresponse in Magnetic van der Waals Crystal TaFeTe2.

2D van der Waals (vdW) materials with broken symmetry, such as MM'Te2 (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 TaFeTe2 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, TaFeTe2-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.