Exploring magnetism of lead-free halide double perovskites: A high-throughput first-principles study

We have performed a comprehensive, first-principles high-throughput study of the magnetic properties of halide double perovskites, Cs2BB'Cl-6, with magnetic ions occupying one or both B and B' sites. Our findings indicate a general tendency for these materials to exhibit antiferromagnetic ordering with low Neel temperatures. At the same time, we reveal a few potential candidates that predicted to be ferromagnetic with relatively high Curie temperatures. Achieving ferromagnetic coupling might be feasible via simultaneously alloying at B and B' sites with magnetic 3d and nonmagnetic 5d ions. With this approach, we discover that Cs2HgCrCl6, Cs2AgNiCl6, and Cs2AuNiCl6 have high Curie temperatures relative to their peers, with the latter two exhibiting half metallic behavior. Further, this study illuminates the underpinning mechanism of magnetic exchange interactions in halide double perovskites, enabling a deeper understanding of their magnetic behavior. Our findings, especially the discovery of the compounds with robust half metallic properties and high Curie temperatures, hold promise for potential applications in the field of spintronics.