17 research outputs found
Hidden covalent insulator and spin excitations in SrRuO
The density functional plus dynamical mean-field theory is used to study the
spin excitation spectra of SrRuO. A good quantitative agreement with
experimental spin excitation spectra is found. Depending on the size of the
Hund's coupling the systems chooses either Mott insulator or covalent
insulator state when magnetic ordering is not allowed. We find that the nature
of the paramagnetic state has negligible influence on the charge and spin
excitation spectra. We find that antiferromagnetic correlations hide the
covalent insulator state for realistic choices of the interaction parameters.Comment: 8 pages, 7 figure
Kondo quasiparticle dynamics observed by resonant inelastic x-ray scattering
Effective models focused on pertinent low-energy degrees of freedom have
substantially contributed to our qualitative understanding of quantum
materials. An iconic example, the Kondo model, was key to demonstrating that
the rich phase diagrams of correlated metals originate from the interplay of
localized and itinerant electrons. Modern electronic structure calculations
suggest that to achieve quantitative material-specific models, accurate
consideration of the crystal field and spin-orbit interactions is imperative.
This poses the question of how local high-energy degrees of freedom become
incorporated into a collective electronic state. Here, we use resonant
inelastic x-ray scattering (RIXS) on CePd to clarify the fate of all
relevant energy scales. We find that even spin-orbit excited states acquire
pronounced momentum-dependence at low temperature - the telltale sign of
hybridization with the underlying metallic state. Our results demonstrate how
localized electronic degrees of freedom endow correlated metals with new
properties, which is critical for a microscopic understanding of
superconducting, electronic nematic, and topological states
Kondo quasiparticle dynamics observed by resonant inelastic x-ray scattering
Effective models focused on pertinent low-energy degrees of freedom have substantially contributed to our qualitative understanding of quantum materials. An iconic example, the Kondo model, was key to demonstrating that the rich phase diagrams of correlated metals originate from the interplay of localized and itinerant electrons. Modern electronic structure calculations suggest that to achieve quantitative material-specific models, accurate consideration of the crystal field and spin-orbit interactions is imperative. This poses the question of how local high-energy degrees of freedom become incorporated into a collective electronic state. Here, we use resonant inelastic x-ray scattering (RIXS) on CePd to clarify the fate of all relevant energy scales. We find that even spin-orbit excited states acquire pronounced momentum-dependence at low temperature—the telltale sign of hybridization with the underlying metallic state. Our results demonstrate how localized electronic degrees of freedom endow correlated metals with new properties, which is critical for a microscopic understanding of superconducting, electronic nematic, and topological states
CaCu3Ru4O12: a high-kondo-temperature transition-metal oxide
遷移金属酸化物の近藤効果を初めて実証 --電子相関物性の設計・探索の新たなプラットホームを開拓--. 京都大学プレスリリース. 2022-01-31.Open access publication funded by the Max Planck Society.We present a comprehensive study of CaCu₃Ru₄O₁₂ using bulk sensitive hard and soft x-ray spectroscopy combined with local-density approximation + dynamical mean-field theory (DMFT) calculations. Correlation effects on both the Cu and Ru ions can be observed. From the Cu 2p core-level spectra, we deduce the presence of magnetic Cu²⁺ ions hybridized with a reservoir of itinerant electrons. The strong photon energy dependence of the valence band allows us to disentangle the Ru, Cu, and O contributions and, thus, to optimize the DMFT calculations. The calculated spin and charge susceptibilities show that the transition metal oxide CaCu₃Ru₄O₁₂ must be classified as a Kondo system and that the Kondo temperature is in the range of 500–1000 K
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Kondo quasiparticle dynamics observed by resonant inelastic x-ray scattering
Effective models focused on pertinent low-energy degrees of freedom have substantially contributed to our qualitative understanding of quantum materials. An iconic example, the Kondo model, was key to demonstrating that the rich phase diagrams of correlated metals originate from the interplay of localized and itinerant electrons. Modern electronic structure calculations suggest that to achieve quantitative material-specific models, accurate consideration of the crystal field and spin-orbit interactions is imperative. This poses the question of how local high-energy degrees of freedom become incorporated into a collective electronic state. Here, we use resonant inelastic x-ray scattering (RIXS) on CePd3 to clarify the fate of all relevant energy scales. We find that even spin-orbit excited states acquire pronounced momentum-dependence at low temperature-the telltale sign of hybridization with the underlying metallic state. Our results demonstrate how localized electronic degrees of freedom endow correlated metals with new properties, which is critical for a microscopic understanding of superconducting, electronic nematic, and topological states