Electronic and ferroelectric properties of Niobium and Titanium-based 2D Janus monolayers

Two-dimensional (2D) ferroelectric materials have emerged as a compelling class of substances distinguished by their distinctive electronic and structural properties. One such class of material is the Janus material, characterized by two distinct faces or sides, each possessing unique properties. Janus materials have been investigated for their piezoelectric characteristics; their potential ferroelectric properties have received comparatively limited attention. Our study aims to investigate ferroelectric behavior in Janus materials, focusing on Niobium and Titanium-based Janus monolayers. Employing density functional theory (DFT), our research unveils in-plane spontaneous polarization in these Nb/Ti oxide dihalides. Furthermore, our findings demonstrate the spontaneous polarization in Janus materials with varying halogen atom arrangements. The 2D Janus TiOClI material exhibits a bandgap of 2.862 eV, a value consistent with the existing literature, and displays a notable spontaneous polarization of 1.988 x 10^-10 C/m, which is close to SnS monolayer. Thus, Janus 2D materials can be useful for non-volatile memories, sensors, and nonlinear optoelectronics. The modeling aspect and the results will be discussed in our presentation.