Electronic structure and magnetic properties of La$_{3}$Ni$_{2}$O$_{7}$ under pressure: active role of the Ni-$d_{x^2-y^2}$ orbitals

Harrison LaBollita; Victor Pardo; Michael R. Norman; Antia S. Botana

paper

Electronic structure and magnetic properties of La $_{3}$ Ni $_{2}$ O $_{7}$ under pressure: active role of the Ni- $d_{x^{2} - y^{2}}$ orbitals

arXiv:2309.17279

Abstract

Following the recent report of superconductivity in the bilayer nickelate La $_{3}$ Ni $_{2}$ O $_{7}$ under pressure, we present an analysis of the electronic and magnetic properties of La $_{3}$ Ni $_{2}$ O $_{7}$ as a function of pressure using correlated density functional theory methods (DFT+ $U$ ). At the bare DFT level, the electronic structure of the ambient and high-pressure phases of La $_{3}$ Ni $_{2}$ O $_{7}$ are qualitatively similar. Upon including local correlation effects within DFT+ $U$ and allowing for magnetic ordering, we find a delicate interplay between pressure and electronic correlations. Within the pressure-correlations phase space, we identify a region (at $U$ values consistent with constrained RPA) characterized by a high spin to low spin transition with increasing pressure. In contrast to previous theoretical work that only highlights the crucial role of the Ni- $d_{z^{2}}$ orbitals in this material, we find that the Ni- $d_{x^{2} - y^{2}}$ orbitals are active upon pressure and drive this rich magnetic landscape. This picture is preserved in the presence of oxygen deficiencies.

main: 8 pages, 4 figures, SI: 8 pages, 7 figures

Electronic structure and magnetic properties of La3​Ni2​O7​ under pressure: active role of the Ni-dx2−y2​ orbitals

Abstract

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Electronic structure and magnetic properties of La $_{3}$ Ni $_{2}$ O $_{7}$ under pressure: active role of the Ni- $d_{x^{2} - y^{2}}$ orbitals