Structural phase transition, s±-wave pairing, and magnetic stripe order in bilayered superconductor La3Ni2O7 under pressure

Abstract

Motivated by the recently discovered high-Tc superconductor La3Ni2O7, we comprehensively study this system using density functional theory and random phase approximation calculations. At low pressures, the Amam phase is stable, containing the Y2− mode distortion from the Fmmm phase, while the Fmmm phase is unstable. Because of small differences in enthalpy and a considerable Y2− 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 La3Ni2O7 is qualitatively different from infinite-layer nickelates and cuprate superconductors.

Magnetism and Superconductivity in the t–J Model of La3Ni2O7 Under Multiband Gutzwiller Approximation

“…According to the DFT calculation, [14] we take 𝑡 intra [17][18][19]48] We use electron volt (eV) as the energy unit throughout this study. With varying pressure, the inter-layer hopping amplitude for orbital 𝑑 𝑧 2 may significantly increase, [35] and our work considers different val-ues of 𝑡 inter 11 (= −0.5, −0.6, −0.7). In addition, the average valence of Ni is 𝑑 8−𝛿 , where 𝛿 is the hole doping.…”

“…Some of these mod-els are predicted to produce 𝑠± pairing symmetry. [15,[31][32][33][34][35][36][37] There are also a few theoretical works about possible magnetism in La3Ni2O7. [46][47][48] However, the interplay between magnetism and superconductivity, which is an extremely important issue in Cu-and Fe-based high-𝑇c superconductivity, has not been carefully studied in the context of La3Ni2O7.…”