Transmutation Engineering Makes a Large Class of Stable and Exfoliable A3BX2 Compounds with Exceptional High Magnetic Critical Temperatures and Exotic Electronic Properties.

We establish a robust protocol for materials innovation based on our proposed transmutation engineering strategy combined with combinatorial chemistry and hierarchical high-throughput screening to make a large class of layered 2D A3BX2 materials. After several rounds of efficient screening, 60 types of easily exfoliable and highly stable A3BX2 monolayers have been obtained. Excitingly, four representative monolayers (ferromagnetic Fe3SiS2 and Fe3GeS2, antiferromagnetic Mn3PbTe2 and Co3GeSe2) demonstrate quite high magnetic critical temperatures of 600 (TC), 630 (TC), 770 (TN), and 510 K (TN), respectively. Through electronic fingerprint identification, the magnetic exchange mechanism is fundamentally unveiled at the atomic level in combination with a local chemical topology environment and crystal/exchange field. Furthermore, two simple and effective unified descriptors are proposed to perfectly explain the origin of magnetic strain regulation. Some intriguing materials (featuring double Dirac cones, node-loops, and ultrahigh Fermi velocities) are expected to be used in high-speed and low-dissipation nanodevices. This material family forms a dataset, which establishes a platform to discover and explore unexpected physicochemcial properties and develop promising applications under different circumstances. The chemical trends of diverse properties for this class of materials are revealed, which offers guiding insights for the development of spintronics and nanoelectronics with the target of exploiting both spin and charge degrees of freedom directed functional materials design and screening.