Structural instabilities of infinite-layer nickelates from first-principles simulations

• Published in: Physical review research Vol. 4; no. 2; p. 023064
• Main Authors: Carrasco Álvarez, Álvaro Adrián, Petit, Sébastien, Iglesias, Lucia, Prellier, Wilfrid, Bibes, Manuel, Varignon, Julien
• Format: Journal Article
• Language: English
• Published: American Physical Society 01.04.2022
• Subjects: Condensed Matter; Materials Science; Physics
• ISSN: 2643-1564; 2643-1564
• DOI: 10.1103/PhysRevResearch.4.023064

Rare-earth nickelates RNiO 2 adopting an infinite-layer phase show superconductivity once La, Pr, or Nd is substituted by a divalent cation. Either in the pristine or doped form, these materials are reported to adopt a highsymmetry, perfectly symmetric, P 4 /mmm tetragonal cell. Nevertheless, bulk compounds are scarce, hindering a full understanding of the role of chemical pressure or strain on lattice distortions that in turn could alter magnetic and electronic properties of the two-dimensional nickelates. Here, by performing a full analysis of the prototypical YNiO 2 compound with first-principles simulations, we identify that these materials are prone to exhibit O 4 group rotations whose type and amplitude are governed by the usual R-to-Ni cation size mismatch. We further show that these rotations can be easily tuned by external stimuli modifying lattice parameters such as pressure or strain. Finally, we reveal that H intercalation is favored for any infinite-layer nickelate member and pushes the propensity of the compounds to exhibit octahedra rotations.