Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session A24: Novel Strongly Correlated d- and f-electron Systems: Experiment and Precision Many-body TheoryInvited
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Sponsoring Units: DCMP Chair: Turan Birol, University of Minnesota Room: Room 237 |
Monday, March 6, 2023 8:00AM - 8:36AM |
A24.00001: Band-Mott mixing in transition metal compounds with embedded-DMFT method and beyond Invited Speaker: Kristjan Haule The exact solutions of the uniform electron gas problem by variational diagrammatic Monte Carlo method at metallic densities [1,2] gave us new insights into the screening in solids and show that in metallic solids the short-range interaction point of view is most appropriate for fast convergence towards the exact solution. This gives us a new understanding of why embedding through the Dynamical Mean Field Theory (DMFT) has been so successful in describing numerous correlated solids. In this talk, I will also show several examples of DFT+embedded DMFT functional predictions verified experimentally, including prediction of electron-phonon coupling in FeSe[3,4] and band-Mott gaps mixing in polar magnets with giant magnetoelectric coupling TMo3O8[7]. I will discuss the feedback effect of incoherent spectra on structural properties of solids, their phonon spectra, as well as electron-phonon coupling[3,4]. I will compare and contrast performance and predictive power of eDMFT with other post-DFT ab-initio methods [5,6], such as GW and hybrid DFT's. Finally, I will discuss the combination of eDMFT with diagrammatic Monte Carlo method that should show rapid convergence with perturbation order in correlated solids. |
Monday, March 6, 2023 8:36AM - 9:12AM |
A24.00002: Unveiling charge, spin, and orbital excitations in correlated d-electron materials by resonant inelastic x-ray scattering Invited Speaker: Matthias Hepting Resonant inelastic x-ray scattering (RIXS) is a powerful technique for momentum- and energy-resolved measurements of charge, spin, and orbital excitations in correlated materials. The dispersion relations of these excitations encode the strength and range of atomic-scale Coulomb and exchange interactions, which are of primary interest in research on the origin of collective instabilities, such as superconductivity and magnetism. |
Monday, March 6, 2023 9:12AM - 9:48AM |
A24.00003: Self-consistent DFT + DMFT Study of Strongly Correlated Electron Systems: Infinite Layer Rare-earth Nickelates Invited Speaker: Khandker F Quader Novel materials whose properties are influenced by the presence of strongly correlated d- and/or f-electrons have been of sustained interest. Among these, the infinite-layer nickelates, RNiO2 (R = Nd, Pr, La), that exhibit superconductivity upon hole-doping, have received considerable attention. Based on self-consistent density functional theory (DFT) + embedded dynamical mean-field theory (eDMFT) calculations, we provide new insights into the physics of the low-energy many-body states of the parent compounds of the infinite layer systems. To appeal to a broad audience, we first elucidate the basic ideas underlying the self-consistent DFT+ eDMFT approach. Then we present results of our calcuations in the paramagnetic and magnetic states of RNiO2. We depict the emergent many-body states, and the associated correlation (U) and temperature (T) scales in a proposed U-T phase diagram. The key features are a low-T Fermi liquid (FL) phase, a high-T Curie-Weiss regime, and an antiferromagnetic phase in a relatively small U-T region. We associate the onset of the FL phase with partial screening of Ni-d electron moments; however, full screening occurs at lower temperatures. This may be related to insufficiency of conduction electrons to effectively screen the Ni-d moments, suggestive of Nozieres Exhaustion Principle. Consistent with the lack of experimental evidence for long-range magnetic order, and recent observation of magnetic excitations in NdNiO2, our results are suggestive of RNiO2 being in the paramagnetic state close to an antiferromagnetic dome, making magnetic fluctuations feasible. This may be consequential for superconductivity. In the end we briefly discuss our more recent work on doped nickelates. |
Monday, March 6, 2023 9:48AM - 10:24AM |
A24.00004: Resonant X-ray spectroscopy studies on infinite-layer nickelates Invited Speaker: Wei-Sheng Lee The recent discovery of superconducting nickelates has drawn significant interest in the field. The nickelate superconductor is a Sr-doped infinite layer nickelate RNiO2, which is isostructural to the infinite-layer cuprates and possesses the same nominal 3d electron count. Experimental investigations of the electronic structure and elementary excitations, such as magnetic excitations, can characterize the similarities and differences to the cuprates, providing important insight into the underlying microscopic mechanism in nickelate superconductors. |
Monday, March 6, 2023 10:24AM - 11:00AM |
A24.00005: Dynamical Vertex Approximation Approach in Strongly Correlated Electron Systems Invited Speaker: Karsten Held Strong electronic correlations pose one of the biggest challenges to solid state theory. Recently methods have been developed [1,2] that address this problem by starting with the important local correlations of dynamical mean field theory (DMFT), but further extend it to nonlocal correlations on all length scales. These non-local correlations are generated through Feynman diagrams, with a local two-particle vertex instead of the bare Coulomb interaction as a building block. These diagrammatic extensions of DMFT have been very successfully used to calculate long-range charge, magnetic, and superconducting fluctuations as well as (quantum) criticality in strongly correlated electron systems [1]. |
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