Signatures of Hund$'s$ metal physics in single-layered 3d transition metal oxide, $\mathrm{Sr_2CoO_4}$

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Main Authors: Bhardwaj, Shivani, Pandey, Sudhir K
Format: Preprint
Published: 2025
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author Bhardwaj, Shivani
Pandey, Sudhir K
author_facet Bhardwaj, Shivani
Pandey, Sudhir K
contents With density functional theory plus dynamical mean-field theory, we study the influence of Hund's coupling on the nature of electronic correlations in $\mathrm{Sr_2CoO_4}$. Our results suggest strong signatures of Hund's metal physics in this compound. The Co 3$d$ states show large orbital differentiation in the degree of correlations and mass enhancement. The imaginary-time correlation functions suggest the presence of spin-orbital separation and large local charge fluctuations in the system. Breakdown of the Fermi-liquid picture is observed at the lowest calculated temperature for various strengths of Hund's coupling, suggesting the Fermi-liquid coherence scale lower than $\sim$100 K. Interestingly, a sudden emergence of a gapped state is noted for $e_g$ orbitals in its spectral density of states at $\sim$200 K in the vicinity of Fermi-level. Among the Co 3$d$ states 3$d_{z^2}$ and 3$d_{x^2-y^2}$ foster enlarged correlations. This study conclusively identifies $\mathrm{Sr_2CoO_4}$ as the first single-layered 3$d$ transition metal oxide to be classified as Hund's metal.
format Preprint
id arxiv_https___arxiv_org_abs_2504_19503
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Signatures of Hund$'s$ metal physics in single-layered 3d transition metal oxide, $\mathrm{Sr_2CoO_4}$
Bhardwaj, Shivani
Pandey, Sudhir K
Strongly Correlated Electrons
With density functional theory plus dynamical mean-field theory, we study the influence of Hund's coupling on the nature of electronic correlations in $\mathrm{Sr_2CoO_4}$. Our results suggest strong signatures of Hund's metal physics in this compound. The Co 3$d$ states show large orbital differentiation in the degree of correlations and mass enhancement. The imaginary-time correlation functions suggest the presence of spin-orbital separation and large local charge fluctuations in the system. Breakdown of the Fermi-liquid picture is observed at the lowest calculated temperature for various strengths of Hund's coupling, suggesting the Fermi-liquid coherence scale lower than $\sim$100 K. Interestingly, a sudden emergence of a gapped state is noted for $e_g$ orbitals in its spectral density of states at $\sim$200 K in the vicinity of Fermi-level. Among the Co 3$d$ states 3$d_{z^2}$ and 3$d_{x^2-y^2}$ foster enlarged correlations. This study conclusively identifies $\mathrm{Sr_2CoO_4}$ as the first single-layered 3$d$ transition metal oxide to be classified as Hund's metal.
title Signatures of Hund$'s$ metal physics in single-layered 3d transition metal oxide, $\mathrm{Sr_2CoO_4}$
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2504.19503