Metallic-semiconducting transition and spin polarized-unpolarized transition in a single molecule with a negative Poisson's ratio.

Different from conventional materials, structures with a negative Poisson's ratio (NPR) contract/expand laterally under a longitudinal compressive/tensile strain, usually exhibiting peculiar features. Through first-principles calculations, we investigate the electronic and transport properties of PdB molecules. Its Poisson's ratio is found to be negative under uniaxial strain along a specific direction.

Edge-modulated dual spin-filter effect in zigzag-shaped buckling AgS nanoribbons.

Unlike MoS2, single-layered Ag2S nanoribbons (Ag2SNRs) exhibit a nonmetal-shrouded and a zigzag-shaped buckling structure and possess two distinct edges, S- or Ag-terminated ones. By performing first principle calculations, the spin-dependent electron transport of Ag2SNRs in a ferromagnetic state has been investigated. It is found that the SS- and AgAg-terminated Ag2SNRs exhibit semi-metallic characteristics, but with opposite spin-polarized directions.

A progressive metal-semiconductor transition in two-faced Janus monolayer transition-metal chalcogenides.

Breaking the symmetry in the out-of-plane direction in two-dimensional materials to trigger distinctive electronic properties has long been predicted. Inspired by the recent progress in the experimental synthesis of a sandwiched S-Mo-Se structure (Janus SMoSe) at the monolayer limit [Zhang et al., ACS Nano, 2017, 11, 8192-8198], we investigate the transport and electronic structure of two-faced XMoY monolayers (X, Y = O, S, Se and Te) through first-principles calculations.