High-throughput screening and classification of layered di-metal chalcogenides

Through employing the layered-crystal determination program based on the topology-scaling algorithm, 450 M_mN_nX_x (M, N = metal elements, X = S, Se) layered di-metal chalcogenides (LDCs) are identified from the 1 602 011 crystalline materials known in two Material Genome databases (Materials Project and OQMD). Their structures are classified into three types, 104 compounds in standard M_mN_nX_x homo-layered structures, 34 in M_mX_x1/N_nX_x2 hetero-layered structures and 312 in large-cation M-intercalated N_nX_x layered structures. 312 cation-intercalated LDCs are mostly composed of large cations such as K, Rb, Cs, Ba and Tl, and are not easy to be exfoliated into few-layer 2-dimensional (2D) structures because of the strong ionic bonding between the large cations and the negatively charged layers. In contrast, the homo-layered and hetero-layered structures may be exfoliated into stable few-layer 2D structures due to the weak inter-layer van der Waals interaction. The band structure screening identifies 34 direct- and 108 indirect-band-gap layered semiconductors from the 450 LDCs, and 24 of them have small in-plane effective masses and thus high mobility of hole or electron carriers. Two stable, direct-band-gap and high-mobility mono-layer semiconductors MgAl₂S₄ and ZnIn₂S₄ are found from group II-III₂-VI₄ LDCs. Furthermore, 83 LDCs composed of the magnetic metal elements are found, which provides new platforms for the search of 2D magnetic crystals similar to Cr₂Ge₂Te₆ with intrinsic ferromagnetism. This work extends the search of layered materials from metal dichalcogenides to ternary chalcogenides and can serve as a map for the future discovery of novel 2D semiconductors and magnetic materials.