Abstract
Hybrid transition metal oxides continue to attract attention due to their multiple degrees of freedom (e.g., lattice, charge, spin, and orbital) and versatile properties. Here we investigate the magnetic and electronic properties of the newly synthesized double perovskite using crystal-field theory, superexchange model analysis, density functional calculations, and parallel tempering Monte Carlo (PTMC) simulations. Our results indicate that has the ()- () charge states. The first nearest-neighboring ions prefer a ferromagnetic coupling, as expected from the Goodenough-Kanamori-Anderson rules, which contradicts the experimental antiferromagnetic (AF) order in . We find that the strong second nearest-neighboring (2NN) AF couplings are frustrated in the fcc sublattices, and they play a major role in determining the observed AF ground state. We also prove that the = 3/2 and = 1/2 states induced by spin-orbit coupling, which would be manifested in low-dimensional (e.g., layered) iridates, are, however, not the case for cubic . Our PTMC simulations show that when the long-range (2NN and 3NN) AF interactions are included, an AF transition with = 66 K would be obtained, and it is well comparable with the experimental 51 K. Meanwhile, we propose a possible 2 noncollinear AF structure for .
1 More- Received 11 March 2022
- Accepted 4 May 2022
DOI:https://doi.org/10.1103/PhysRevB.105.184413
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