Magnetic phase diagram of a two-orbital model for bilayer nickelates with varying doping
Ling-Fang Lin, Yang Zhang, Nitin Kaushal, Gonzalo Álvarez, Thomas Maier, Adriana Moreo, Elbio Dagotto
Abstract
Motivated by the discovery of bilayer nickelate superconductor La${}_{3}$Ni${}_{2}$O${}_{7}$, the authors investigate here magnetic phase diagrams with varying electronic densities $n$ in a bilayer 2\ifmmode\times\else\texttimes\fi{}2\ifmmode\times\else\texttimes\fi{}2 cluster. Rich magnetic states are observed, which can be understood by three main coupling mechanisms: (1) half-empty ferromagnetic (FM) coupling, (2) half-half antiferromagnetic (AFM) coupling, and (3) half-full FM coupling. At the half-filling case, the half-half mechanism leads to a robust (\ensuremath{\pi}, \ensuremath{\pi}, \ensuremath{\pi}) state. For the La${}_{3}$Ni${}_{2}$O${}_{7}$ ($n$=1.5) case, the AFM coupling is found to be strong along the $z$ axis, while the $x\phantom{\rule{0}{0ex}}y$ plane shows strong competition between AFM and FM tendencies.