Orbital-decomposed electronic and magnetic properties of the double perovskite Sr2FeReO6

The detailed orbital-decomposed electronic structures and magnetic properties of the double perovskite Sr2FeReO6 have been studied using the first-principles projector augmented wave (PAW) potential within the generalized gradient approximation (GGA). Both occupied and unoccupied s and three p states of Fe3+ ion are located far away from the Fermi level, while all up-spin states and most down-spin states are completely filled for the s and three p states of Re5+ ion. The octahedral crystal field of the oxygen atoms around transition-metal (TM) sites splits the five-fold degenerate d states of the free TM atoms into triply degenerate t2g states with smaller bonding–antibonding splitting and doubly degenerate eg states with larger bonding–antibonding splitting. The Fe3+ and Re5+ ions are in the states (3d5, S=5/2) and (5d2, S=1) with magnetic moments 3.70 and −0.86μB, respectively and thus antiferromagnetic coupling via oxygen between them. There are no direct interactions between two nearest Fe–Fe or Re–Re pairs, whereas along each Fe–O–Re–O–Fe or Re–O–Fe–O–Re chains, the hybridizations between Fe 3d and 4s, O 2s and 2p, as well as Re 5p, 5d and 6s orbitals are fairly significant.