Electronic structure, and magnetic and superconducting pairing tendencies of the alternating single layer–bilayer stacking nickelate La5Ni3O11 under pressure

Abstract

Nickelates have continued to surprise since their unconventional superconductivity was discovered. Recently, the layered nickelate La5Ni3O11 with hybrid single-layer and bilayer stacking showed superconductivity under high pressure. This compound combines features of single-layer La2NiO4 and bilayer La3Ni2O7, but its pairing mechanism remains to be understood. Motivated by this finding, here we report a comprehensive theoretical study of this system. Our density functional theory calculations reveal that the undistorted P4/mmm phase without pressure is unstable due to three distortion modes. As pressure increases, these modes are suppressed, leading to the high-symmetry P4/mmm phase without NiO6 octahedron tilting. Moreover, the “charge transfer” between the single-layer and bilayer sublattices was observed, leading to hole doping in the single-layer blocks. Our random-phase approximation calculations indicate a leading dx2−y2-wave pairing state that arises from spin-fluctuation scattering between Fermi surface states mainly originating from the single-layer blocks and additional weaker contributions from the bilayer blocks. These spin fluctuations could be detected by inelastic neutron scattering as a strong peak at q=(π,π). Our findings distinguish La5Ni3O11 from other nickelate superconductors discovered so far and the high-Tc cuprates. We also discuss both similarities and differences between La5Ni3O11 and other hybrid stacking nickelates.

Source-reported materials — not catalogue approval

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