paper

Electronic structure and magnetic tendencies of trilayer LaNiO under pressure: structural transition, molecular orbitals, and layer differentiation

arXiv:2402.05085 · doi:10.1103/PhysRevB.109.195151

Abstract

Motivated by the recent observation of superconductivity in the pressurized trilayer LaNiO Ruddlesden-Popper (RP) nickelate, we explore its structural, electronic, and magnetic properties as a function of hydrostatic pressure from first-principles calculations. We find that in both the bilayer and trilayer nickelates, an orthorhombic(monoclinic)-to-tetragonal transition under pressure takes place concomitantly with the onset of superconductivity. The electronic structure of LaNiO can be understood using a molecular trimer basis wherein molecular subbands arise as the orbitals hybridize strongly along the -axis within the trilayer. The magnetic tendencies indicate that the ground state at ambient pressure is formed by nonmagnetic inner planes and stripe-ordered outer planes that are antiferromagnetically coupled along the axis, resulting in an unusual , 0, stacking that is consistent with the spin density wave model suggested by neutron diffraction. Such a state is destabilized by the pressures wherein superconductivity arises. Despite the presence of states at the Fermi level, the orbitals also play a key role in the electronic structure of LaNiO. This active role of the states in the low-energy physics of the trilayer RP nickelate, together with the distinct electronic behavior of inner and outer planes, resembles the physics of multilayer cuprates.

11 pages, 8 figures

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