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.

Manipulation of the valley degree of freedom provides a novel paradigm in quantum information technology. In this work, through first principles calculations, we demonstrate that monolayer $\mathrm{Gd}{\mathrm{I}}_2$ is a promising candidate material for valleytronic applications. Monolayer $\mathrm{Gd}{\mathrm{I}}_2$ can be easily exfoliated from bulk, and it is spontaneously valley polarized with a giant splitting of 149 meV due to its intrinsic ferromagnetism and large spin orbital coupling. The anomalous valley Hall effect could be realized in monolayer $\mathrm{Gd}{\mathrm{I}}_2$ by an appropriate external electric field. Furthermore, the valley polarization feature is stable against the biaxial in-plane strain. Our findings provide an extraordinary and potential material platform for experimental studies and practical applications in the emergent field of valleytronics.