Motivated by the recently discovered high- T c superconductor La 3Ni 2O 7, we comprehensively study this system using density functional theory and random phase approximation calculations. At low pressures, the Amam phase is stable, containing the Y 2− mode distortion from the Fmmm phase, while the Fmmm phase is unstable. Because of small differences in enthalpy and a considerable Y 2− mode amplitude, the two phases may coexist in the range between 10.6 and 14 GPa, beyond which the Fmmm phase dominates. In addition, the magnetic stripe-type spin order with wavevector ( π, 0) was stable at the intermediate region. Pairing is induced in the s ±-wave channel due to partial nesting between the M = ( π, π) centered pockets and portions of the Fermi surface centered at the X = ( π, 0) and Y = (0, π) points. This resembles results for iron-based superconductors but has a fundamental difference with iron pnictides and selenides. Moreover, our present efforts also suggest La 3Ni 2O 7 is qualitatively different from infinite-layer nickelates and cuprate superconductors.
Recently superconductivity with T c of about 80 K was discovered in a bilayer nickelate La 3Ni 2O 7 under high pressure. Here the authors report a density functional theory and random phase approximation study of structural and electronic properties as a function of pressure and discuss the pairing mechanism.