In this express, we demonstrate few-layer orthorhombic arsenene is an ideal semiconductor. Due to the layer stacking, multilayer arsenenes always behave as intrinsic direct bandgap semiconductors with gap values of around 1 eV. In addition, these bandgaps can be further tuned in its nanoribbons.Based on the so-called acoustic phonon limited approach, the carrier mobilities are predicted to approach as high as several thousand square centimeters per volt-second and simultaneously exhibit high directional anisotropy. All these make few-layer arsenene promising for device applications in semiconducting industry.

Recent experiment shows that the K ′ K valley degeneracy can be lifted in a monolayer WSe2 deposited on a layered ferromagnetic substrate of CrI3. In this work, we take a van der Waals heterostructure WSe2/CrI3 to model the monolayer WSe2 on the CrI3 substrate and investigate the effects underpinning the K ′ K valley splitting based on first-principles calculations. We demonstrate that the interfacial atom superposition plays an important role and a W-Cr superposition is essential for a relatively large valley splitting. The results indicate inevitable sample-to-sample variations in the K ′ K valley splitting in the WSe2/CrI3. Furthermore, we show that the K ′ K valley splitting can be tuned in a trilayer CrI3/WSe2/CrI3 from nearly zero to more than two times of that in the bilayer WSe2/CrI3 by manipulating the layer alignment.

A material exhibiting a negative Poisson's ratio is always one of the leading topics in materials science, which is due to the potential applications in those special areas such as defence and medicine. In this letter, we demonstrate a new material, few-layer orthorhombic arsenic, also possesses the negative Poisson's ratio. For monolayer arsenic, the negative Poisson's ratio is predicted to be around -0.09, originated from the hinge-like structure within the single layer of arsenic. When the layer increases, the negative Poisson's ratio becomes more negative and finally approaches the limit at four-layer, which is very close to the bulk's value of -0.12. The underlying mechanism is proposed for this layer-dependent negative Poisson's ratio, where the internal bond lengths as well as the normal Poisson's ratio within layer play a key role. The study like ours sheds new light on the physics of negative Poisson's ratio in those hinge-like nano-materials.

We report on the design of ultraviolet (UV) emitting persistent (PersL) materials.