Charge Density Wave-Induced Highly Sensitive Terahertz Detection Based on a Large Nonlinear Hall Effect.

Charge density wave (CDW), a collective mode, hosts rich correlated phenomena, including Mott insulator, quantum spin liquid, and flat band in van der Waals material 1T-TaS2. Among these, flat bands condense Berry curvature and electronic states into a point of energy, which dramatically amplifies physical effects such as the nonlinear Hall effect (NLHE). Here, we report the observation of a large room-temperature NLHE in the CDW state of 1T-TaS2 with an estimated Berry curvature dipole of above 10 nm. The zero-diagonal nonlinear transport tensor is revealed despite the presence of C3 symmetry in the NLHE, which reveals the dynamic coupling of CDW with current. Remarkably, based on the NLHE of 1T-TaS2, self-powered terahertz detection at 0.1 THz achieves a record responsivity of 69.72 A/W (9060 V/W) and an incident photon-to-electron conversion efficiency of 3.14% at room temperature. Theoretical modeling indicates that flat-band-driven enhanced Berry curvature is attributed to these state-of-the-art NLHE and terahertz detection capabilities. The CDW-induced Mott bandgap protects the NLHE up to room temperature. These findings establish CDW systems as promising platforms for advancing high-sensitivity wireless terahertz detection.