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arXiv · 2406.13634

Intertwined superconductivity and orbital selectivity in a three-orbital Hubbard model for the iron pnictides

Vito Marino·Alberto Scazzola·Federico Becca·Massimo Capone·Luca F. Tocchio
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Abstract

We study a three-orbital Hubbard-Kanamori model relevant for iron-based superconductors using variational wave functions explicitly including spatial correlations and electron pairing. We span the nonmagnetic sector from filling $n=4$, which is representative of undoped iron-based superconductors, to $n=3$, where a Mott insulating state with each orbital at half filling is found. In the strong-coupling regime, when the electron density is increased, we find a spontaneous differentiation between the occupation of $d_{xz}$ and $d_{yz}$ orbitals, leading to an orbital-selective state with a nematic character that becomes stronger at increasing density. One of these orbitals stays half-filled for all densities while the other one hosts (together with the $d_{xy}$ orbital) the excess of electron density. Most importantly, in this regime long-range pairing correlations appear in the orbital with the largest occupation. Our results highlight a strong link between orbital-selective correlations, nematicity, and superconductivity, which requires the presence of a significant Hund's coupling.

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Vito Marino, Alberto Scazzola, Federico Becca, Massimo Capone, Luca F. Tocchio. 2024-06-19. Intertwined superconductivity and orbital selectivity in a three-orbital Hubbard model for the iron pnictides. https://doi.org/10.1103/physrevlett.134.196502

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