Self-intercalated 6R-TaS₂ with reduced symmetry for room temperature nonlinear Hall effect

The coexistence of multiple phases in two-dimensional (2D) materials enables exotic functionalities via inter-phase proximity and charge effects, but the controlled growth mechanism for heterophase 2D superlattices remains elusive. Herein, we successfully grew a highly crystalline self-intercalated 2D 6R-phase TaS₂ (ic-2D 6R-TaS₂) crystal by chemical vapor transport. A robust in-plane nonlinear Hall effect (NLHE) was observed in low symmetrical ic-2D 6R-TaS₂ material (C_1v), i.e., 2–3 orders of magnitude higher than WTe₂ and MoTe₂. Density functional theory (DFT) calculations revealed a strong Berry curvature dipole in the ic-2D 6R-TaS₂ crystal, triggered by band crossings near the Fermi level and universally present in a library of ic-2D transition metal dichalcogenide (TMDC) heterophase superlattices, e.g., Nb_1+xS₂, Ta_1+xSe₂, etc. Our findings thus provide the atomic insights for the intercalated stabilized growth mechanism of heterophase superlattices and propose a class of ic-2D heterophase TMDC superlattices as potential candidates for NLHE nanodevices.