Two-dimensional (2D) materials have been a hot research topic in the last decade, due to novel fundamental physics in the reduced dimension and appealing applications. Systematic discovery of functional 2D materials has been the focus of many studies. Here, we present a large dataset of 2D materials, with more than 6,000 monolayer structures, obtained from both top-down and bottom-up discovery procedures. First, we screened all bulk materials in the database of Materials Project for layered structures by a topology-based algorithm and theoretically exfoliated them into monolayers. Then, we generated new 2D materials by chemical substitution of elements in known 2D materials by others from the same group in the periodic table. The structural, electronic and energetic properties of these 2D materials are consistently calculated, to provide a starting point for further material screening, data mining, data analysis and artificial intelligence applications. We present the details of computational methodology, data record and technical validation of our publicly available data (http://www.2dmatpedia.org/).

As Moore's law is gradually losing its effectiveness, the development of alternative high-speed and low-energy–consuming information technology with postsilicon-advanced materials is urgently needed. The successful application of tunneling magnetoresistance (TMR) in magnetic tunnel junctions (MTJs) has given rise to a tremendous economic impact on magnetic informatics, including magnetoresistive random access memory (MRAM), radiofrequency sensors, microwave generators, and neuromorphic computing networks. The emergence of two-dimensional (2D) materials brings opportunities for MTJs based on 2D materials, which have many attractive characteristics and advantages. In particular, the recently discovered intrinsic 2D ferromagnetic materials with high spin polarization hold the promise for next-generation nanoscale MTJs. Various 2D materials, such as semimetallic graphene, insulating h-BN, semiconducting MoS₂, magnetic semiconducting CrI₃, magnetic metallic Fe₃GeTe₂, and some other recently emerged 2D materials, are discussed as the electrodes and/or central scattering materials of MTJs in this review. We discuss the fundamental and main issues facing MTJs; review the current progress made with 2D MTJs; briefly comment on work with some specific 2D materials and highlight how they address the current challenges in MTJs; and, finally, offer an outlook and perspective of 2D MTJs.

By combining density functional theory and nonequilibrium Green's function, we study the electronic and transport properties of monolayer black phosphorus nanoribbons (PNRs). First, we investigate the band gap of PNRs and its modulation by the ribbon width and an external transverse electric field. Our calculations indicate a giant Stark effect in PNRs, which can switch on transport channels of semiconducting PNRs under low bias, inducing an insulator-metal transition. Next, we study the transport channels in PNRs via the calculations of the current density and local electron transmission pathway. In contrast to graphene and ${\mathrm{MoS}}_2$ nanoribbons, the carrier transport channels under low bias are mainly located in the interior of both armchair and zigzag PNRs, and immune to a small amount of edge defects. Last, a device of the PNR-based dual-gate field-effect transistor, with high on/off ratio of ${10}^3$, is proposed based on the giant electric-field tuning effect.