Effects of chemical and hydrostatic pressures on structural, magnetic, and electronic properties of R2NiMnO6 (R = rare-earth ion) double perovskites

The effects of chemical and hydrostatic pressures on structural, magnetic, and electronic properties of R2NiMnO6 double perovskites, with R being a rare-earth ion, have been systematically studied by using specific first-principles calculations. These latter reproduce well the correlation between several properties (e.g., lattice parameters, Ni-O-Mn bond angles, magnetic Curie temperature, and electronic band gap) and the rare-earth ionic radius (i.e., the chemical pressure). They also provide novel predictions awaiting experimental confirmation, such as (i) that many physical quantities respond in dramatically different manners to chemical versus hydrostatic pressure, unlike as commonly thought for perovskites containing rare-earth ions, and (ii) a dependence of antipolar displacements on chemical and hydrostatic pressures, which would further explain why the recently predicted electrical polarization of La2NiMnO6/R2NiMnO6 superlattices [H. J. Zhao, W. Ren, Y. Yang, J. Iniguez, X. M. Chen, and L. Bellaiche, Nat. Commun. 5, 4021 (2014)] can be created and controlled by playing with the rare-earth element.