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arXiv · 2312.11457

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

Fabian B. Kugler·Chang-Jong Kang·Gabriel Kotliar
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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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Fabian B. Kugler, Chang-Jong Kang, Gabriel Kotliar. 2023-12-18. Low-energy perspective on two-orbital Hund metals and the case of LaNiO2. https://doi.org/10.1103/physrevb.110.155101

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