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.