Low-energy perspective on two-orbital Hund metals and the case of LaNiO2

Abstract

The Hund-metal route to strong correlations continues to attract large interest in the condensed-matter community. The question arose to what extent it applies to the infinite-layer nickelates and, as a related question, to two-orbital systems in general. Here, we provide a low-energy perspective on this topic through a dynamical mean-field study using the numerical renormalization group (NRG) as a real-frequency impurity solver. We find that the RG flow from high to low energy is a uniquely adequate tool to reveal two-stage Kondo screening (2SKS), a fascinating mechanism for Hund physics. Further, we show that 2SKS takes place in a quarter-filled two-orbital system, but can be easily suppressed by a sufficiently large crystal-field splitting. We apply these insights to LaNiO2 using a recently proposed two-orbital model and show that it is indeed the crystal-field splitting that suppresses multiorbital phenomena in this scenario. Our general findings open the way for further explorations of 2SKS, and we propose a way of reviving low-energy Hund physics in LaNiO2 by counteracting the crystal field.

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Cited by in corpus (7)

• LiV2O4: Hund-Assisted Orbital-Selective Mottness
• Fermi-Liquid $T^2$ Resistivity: Dynamical Mean-Field Theory Meets Experiment
• Observation of Electride-like $s$ States Coexisting with Correlated $d$ Electrons in NdNiO${}_2$
• Testing the parquet equations and the U(1) Ward identity for real-frequency correlation functions from the multipoint numerical renormalization group
• Low-temperature transport in high-conductivity correlated metals: a density-functional plus dynamical mean-field study of cubic perovskites
• Hund flat band in a frustrated spinel oxide
• Impact of strong electronic correlations on altermagnets: the case of NiS2