Hund-Heisenberg model in superconducting infinite-layer nickelates

Abstract

We theoretically investigate the unconventional superconductivity in the newly discovered infinite-layer nickelates Nd${}_{1-x}$Sr${}_x$NiO${}_2$ based on a two-band model. By analyzing the transport experiments, we propose that the doped holes dominantly enter the Ni $d_{xy}$ or/and $d_{3z^2-r^2}$ orbitals as charged carriers, and form a conducting band. Via the onsite Hund coupling, the doped holes are coupled to the Ni localized holes in the $d_{x^2-y^2}$ orbital band. We demonstrate that this two-band model could be further reduced to a Hund-Heisenberg model. Using the reduced model, we show the non-Fermi liquid state above the critical $T_c$ could stem from the carriers coupled to the spin fluctuations of the localized holes. In the superconducting phase, the short-range spin fluctuations mediate the carriers into Cooper pairs and establish $d_{x^2-y^2}$-wave superconductivity. We further predict that the doped holes ferromagnetically coupled with the local magnetic moments remain itinerant even at very low temperature, and thus the pseudogap hardly emerges in nickelates. Our work provides a new superconductivity mechanism for strongly correlated multi-orbital systems and paves a distinct way to exploring new superconductors in transition or rare-earth metal oxides.

the paper was expanded, 7 pages, 1 figure

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Cited by in corpus (20)

• Superconducting Dome in Nd${}_{1-x}$Sr${}_x$NiO${}_2$ Infinite Layer Films
• Superconductivity in infinite-layer nickelates
• Orbital and Spin Character of Doped Carriers in Infinite-Layer Nickelates
• Electronic Structure Trends Across the Rare-Earth Series in Superconducting Infinite Layer Nickelates
• Optical properties of the infinite-layer La${}_{1-x}$Sr${}_x$NiO${}_2$ and hidden Hund's physics
• $f$-electron and magnetic ordering effects in nickelates LaNiO${}_2$ and NdNiO${}_2$: remarkable role of the cuprate-like $3d_{x^2-y^2}$ band
• Magnetic correlations in infinite-layer nickelates: an experimental and theoretical multi-method study
• Preparation of superconducting thin films of infinite-layer nickelate Nd${}_{0.8}$Sr${}_{0.2}$NiO${}_2$
• Doping-dependent character and possible magnetic ordering of NdNiO${}_2$
• Trilayer multi-orbital models of $\mathrm{L}{\mathrm{a}}_4\mathrm{N}{\mathrm{i}}_3{\mathrm{O}}_{10}$
• Polarity induced electronic and atomic reconstruction at NdNiO2/SrTiO3 interfaces
• Doping dependence of electronic structure of infinite-layer NdNiO2
• Strongly correlated doped hole carriers in the superconducting nickelates: Their location, local many-body state, and low-energy effective Hamiltonian
• Experimental Evidence that Zn Impurities Pin Pair-Density-Wave Order in La${}_{2-x}$Ba${}_x$CuO${}_4$
• Core-level x-ray photoemission and Raman spectroscopy studies on electronic structures in Mott-Hubbard type nickelate oxide NdNiO${}_2$
• Possible structural quantum criticality tuned by rare-earth ion substitution in infinite-layer nickelates
• Softening of $dd$ excitation in the resonant inelastic x-ray scattering spectra as a signature of Hund's coupling in nickelates
• Emergent half-metal with mixed structural order in (111)-oriented (LaMnO${}_3$)${}_{2n}$|(SrMnO${}_3$)${}_n$ superlattices
• $\text{Ab initio}$ Materials Design of Superconductivity in $d^9$ Nickelates
• A $d^8$ anti-Hund's Singlet Insulator in an Infinite-layer Nickelate