Published March 2, 2023 | Version v1
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Hybridization driving distortions and multiferroicity in rare-earth nickelates

  • 1. Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
  • 2. Laboratory for Materials Simulations, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland

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Description

For decades transition-metal oxides have generated a huge interest due to the multitude of physical phenomena they exhibit. In this class of materials, the rare-earth nickelates, RNiO₃, stand out for their rich phase diagram stemming from complex couplings between the lattice, electronic and magnetic degrees of freedom. Here, we present a first-principles study of the low-temperature phase for two members of the RNiO₃ series, with R = Pr, Y. We employ density-functional theory with Hubbard corrections accounting not only for the on-site localizing interactions among the Ni-3d electrons (U), but also the inter-site hybridization effects between the transition-metals and the ligands (V). All the U and V parameters are calculated from first-principles using density-functional perturbation theory, resulting in a fully ab initio methodology. Our simulations show that the inclusion of the inter-site interaction parameters V is necessary to simultaneously capture the features well-established by experimental characterizations of the low-temperature state: insulating character, antiferromagnetism and bond disproportionation. On the contrary, for some magnetic orderings the inclusion of on-site interaction parameters U alone completely suppresses the breathing distortion occurring in the low-temperature phase and produces an erroneous electronic state with a vanishing band gap. In addition - only when both the U and V are considered - we predict a polar phase with a magnetization-dependent electric polarization, supporting very recent experimental observations that suggest a possible occurrence of type-II multiferroicity for these materials.

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References

Journal reference
L. Binci, M. Kotiuga, I. Timrov, N. Marzari, Physical Review Research 5, 033146 (2023), doi: 10.1103/PhysRevResearch.5.033146

Preprint
L. Binci, M. Kotiuga, I. Timrov, N. Marzari, arXiv preprint (2023), doi: 10.48550/arXiv.2212.12529