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Two‐dimensional (2D) transition metal dichalcogenides (TMDCs) such as MoS₂exhibit exceptionally strong nonlinear optical responses, while nanoscale control of the amplitude, polar orientation, and phase of the nonlinear light in TMDCs remains challenging. In this work, by interfacing monolayer MoS₂with epitaxial PbZr_0.2Ti_0.8O₃(PZT) thin films and free‐standing PZT membranes, the amplitude and polarization of the second harmonic generation (SHG) signal are modulated via ferroelectric domain patterning, which demonstrates that PZT membranes can lead to in‐operando programming of nonlinear light polarization. The interfacial coupling of the MoS₂polar axis with either the out‐of‐plane polar domains of PZT or the in‐plane polarization of domain walls tailors the SHG light polarization into different patterns with distinct symmetries, which are modeled via nonlinear electromagnetic theory. This study provides a new material platform that enables reconfigurable design of light polarization at the nanoscale, paving the path for developing novel optical information processing, smart light modulators, and integrated photonic circuits.

The van der Waals magnets CrX₃(X = I, Br, and Cl) exhibit highly tunable magnetic properties and are promising candidates for developing novel two‐dimensional (2D) spintronic devices such as magnetic tunnel junctions and spin tunneling transistors. Previous studies of the antiferromagnetic CrCl₃have mainly focused on mechanically exfoliated samples. Controlled synthesis of high quality atomically thin flakes is critical for their technological implementation but has not been achieved to date. This work reports the growth of large CrCl₃flakes down to monolayer thickness via the physical vapor transport technique. Both isolated flakes with well‐defined facets and long stripe samples with the trilayer portion exceeding 60 µm have been obtained. High‐resolution transmission electron microscopy studies show that the CrCl₃flakes are single crystalline in the monoclinic structure, consistent with the Raman results. The room temperature stability of the CrCl₃flakes decreases with decreasing thickness. The tunneling magnetoresistance of graphite/CrCl₃/graphite tunnel junctions confirms that few‐layer CrCl₃possesses in‐plane magnetic anisotropy and Néel temperature of 17 K. This study paves the path for developing CrCl₃‐based scalable 2D spintronic applications.