| 1. |
- Kugler, Fabian B., et al.
(författare)
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Strongly Correlated Materials from a Numerical Renormalization Group Perspective : How the Fermi-Liquid State of Sr2RuO4 Emerges
- 2020
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Ingår i: Physical Review Letters. - New York : American Physical Society. - 0031-9007 .- 1079-7114. ; 124:1
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Tidskriftsartikel (refereegranskat)abstract
- The crossover from fluctuating atomic constituents to a collective state as one lowers temperature or energy is at the heart of the dynamical mean-field theory description of the solid state. We demonstrate that the numerical renormalization group is a viable tool to monitor this crossover in a real-materials setting. The renormalization group flow from high to arbitrarily small energy scales clearly reveals the emergence of the Fermi-liquid state of Sr2RuO4. We find a two-stage screening process, where orbital fluctuations are screened at much higher energies than spin fluctuations, and Fermi-liquid behavior, concomitant with spin coherence, below a temperature of 25 K. By computing real-frequency correlation functions, we directly observe this spin-orbital scale separation and show that the van Hove singularity drives strong orbital differentiation. We extract quasiparticle interaction parameters from the low-energy spectrum and find an effective attraction in the spin-triplet sector.
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| 2. |
- Strand, Hugo, 1983-, et al.
(författare)
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Magnetic response of Sr2RuO4 : quasi-local spin fluctuations due to Hund’s coupling
- 2019
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - New York : American Physical Society. - 1098-0121 .- 1550-235X. ; 100:12
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Tidskriftsartikel (refereegranskat)abstract
- We study the magnetic susceptibility in the normal state of Sr2RuO4 using dynamical mean-field theory including dynamical vertex corrections. Besides the well known incommensurate response, our calculations yield quasi-local spin fluctuations which are broad in momentum and centered around the Gamma-point, in agreement with recent inelastic neutron scattering experiments [Steffens et al., Phys. Rev. Lett. 122, 047004 (2019)]. We show that these quasi-local fluctuations are controlled by the Hund’s coupling and account for the dominant contribution to the momentum-integrated response. While all orbitals contribute equally to the incommensurate response, the enhanced Gamma-point response originates from the planar xy orbital.
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| 3. |
- Tamai, Anna, et al.
(författare)
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High-Resolution Photoemission on Sr2RuO4 Reveals Correlation-Enhanced Effective Spin-Orbit Coupling and Dominantly Local Self-Energies
- 2019
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Ingår i: Physical Review X. - New York : American Physical Society. - 2160-3308. ; 9:2
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Tidskriftsartikel (refereegranskat)abstract
- We explore the interplay of electron-electron correlations and spin-orbit coupling in the model Fermi liquid Sr2RuO4 using laser-based angle-resolved photoemission spectroscopy. Our precise measurement of the Fermi surface confirms the importance of spin-orbit coupling in this material and reveals that its effective value is enhanced by a factor of about 2, due to electronic correlations. The self-energies for the β and γ sheets are found to display significant angular dependence. By taking into account the multi-orbital composition of quasiparticle states, we determine self-energies associated with each orbital component directly from the experimental data. This analysis demonstrates that the perceived angular dependence does not imply momentum-dependent many-body effects but arises from a substantial orbital mixing induced by spin-orbit coupling. A comparison to single-site dynamical mean-field theory further supports the notion of dominantly local orbital self-energies and provides strong evidence for an electronic origin of the observed nonlinear frequency dependence of the self-energies, leading to “kinks” in the quasiparticle dispersion of Sr2RuO4.
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