Rational Design of Magnetic Hybrid Transition Metal Double Perovskites in Polyatomic Anionic Systems

Motivated by the exciting magnetic properties exhibited by inorganic transition metal based double perovskites A2BB′O6, we computationally explore designing of hybrid double perovskites with transition metal elements at the B sublattice. We focus our attention on compounds with the organic group methylammonium (MA+) at the A site and polyatomic cyanide, (CN)−, as the molecular linker. This restricts our search to the monovalent/divalent cation at the B site and trivalent/divalent cations at the B′ site. Fixing Cu as the choice of cation at the B site, we scan the elemental space of the 3d, 4d, and 5d transition metal series. Our study reveals an interesting interplay of electronegativity, crystal field, and filling effect in structural, electronic, and magnetic properties of these yet-to-be synthesized compounds. Several of the proposed compounds are found to be strongly magnetic with antiferromagnetic coupling and moderately high Neél temperature. Our computational study involving Ag in place of Cu provides rare examples of Ag­(II) compounds.