Purely one-dimensional ferroelectricity and antiferroelectricity from van der Waals niobium oxide trihalides

Abstract Intrinsic one-dimensional (1D) ferroelectric materials are rarely reported but are highly sought to break the size limit of nanostructured conventional ferroelectrics. Herein, we report a class of inborn 1D ferroelectric nanowires, namely 1D NbOX 3 (X = Cl, Br, and I), that can be directly obtained from experimentally realized van der Waals crystals. In addition to the sizable spontaneous polarization, 1D NbOX 3 exhibits low ferroelectric switching barriers, small coercive electric fields, and high critical temperature, governed by the hybridization of the Nb empty d orbitals and the O p orbitals ( d 0 rule). Moreover, the double-channel structure of 1D NbOX 3 also enables the emergence of 1D antiferroelectric metastable states. Our findings not only propose a class of 1D ferroelectric materials toward the development of miniaturized and high-density electronic devices, but also pave an avenue of obtaining intrinsic 1D ferroelectrics from van der Waals crystals.