2025/03/13 by Geisler, Benjamin, Hamlin, James J., Stewart, Gregory R. +2
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Superconductivity (cond-mat.supr-con)
paper · doi:10.48550/arxiv.2503.10902
Motivated by the recent observation of ambient-pressure superconductivity with Tc ∼ 40 K in La3Ni2O7 on SrLaAlO4(001) (SLAO), we explore the structural and electronic properties as well as the spin-spin correlation function of this bilayer nickelate system by using density functional theory including a Coulomb repulsion term. We find that the compressive strain exerted by this substrate leads to an unconventional occupation of the antibonding Ni 3dz2 states around the Γ point, distinct from the superconducting bulk compound under pressure. While pure strain effects rather modestly enhance the dynamical spin susceptibility, investigation of a reconstructed interface composition as observed in transmission electron microscopy uncovers a strong amplification of the spin fluctuations due to Fermi surface nesting of the antibonding Ni 3dz2 states near the interface. These results provide insights into the emergence of superconductivity in strained La3Ni2O7, suggest a possible key role of the interface, and highlight fundamental differences from the hydrostatic pressure scenario.