Colossal Room-Temperature Terahertz Topological Response in Type-II Weyl Semimetal NbIrTe₄

The electromagnetic spectrum between microwave and infrared light is termed the "terahertz (THz) gap," of which there is an urgent lack of feasible and efficient room-temperature (RT) THz detectors. Type-II Weyl semimetals (WSMs) have been predicted to host significant RT topological photoresponses in low-frequency regions, especially in the THz gap, well addressing the shortcomings of THz detectors. However, such devices have not been experimentally realized yet. Herein, a type-II WSM (NbIrTe₄ ) is selected to fabricate THz detector, which exhibits a photoresponsivity of 5.7 × 10⁴  V W^-1 and a one-year air stability at RT. Such excellent THz-detection performance can be attributed to the topological effect of type-II WSM in which the effective mass of photogenerated electrons can be reduced by the large tilting angle of Weyl nodes to further improve mobility and photoresponsivity. Impressively, this device shows a giant intrinsic anisotropic conductance (σ_max /σ_min  = 339) and THz response (I_ph-max /I_ph-min  = 40.9), both of which are record values known. The findings open a new avenue for the realization of uncooled and highly sensitive THz detectors by exploring type-II WSM-based devices.