1/6/2024 0 Comments Qspace nrg![]() In the Fermi-liquid regime, anondegenerate collective ground state is formed, with long-lived coherent quasiparticle excitations and susceptibilitiesdisplaying Pauli behavior. In correlatedmetals, these fluctuations are suppressed as one reacheslow temperature and energy. In materialswith strong electronic correlations, these local fluctuationscan be observed at high temperature and energy through,e.g., Curie–Weiss-like spin susceptibilities. Introduction.-Ītoms with partially filled shells havea spectrum of many-body eigenstates with degeneraciesassociated with fluctuating spin and orbital moments.For instance, the isolated ruthenium atom in the Ru configuration, subject to an octahedral crystal field, hasa ninefold degenerate ground state corresponding to spinand orbital quantum numbers S = L = 1. ![]() We extract quasiparticle interactionparameters from the low-energy spectrum and find an effective attraction in the spin-triplet sector. By computingreal-frequency correlation functions, we directly observe this spin–orbital scale separation and showthat the van Hove singularity drives strong orbital differentiation. We find a two-stage screeningprocess, where orbital fluctuations are screened at much higher energies than spin fluctuations, andFermi-liquid behavior, concomitant with spin coherence, below a temperature of 25 K. The renormalization group flow from high to arbitrarily small energy scalesclearly reveals the emergence of the Fermi-liquid state of Sr RuO. Wedemonstrate that the numerical renormalization group is a viable tool to monitor this crossover in areal-materials setting. Lee, Jan von Delft, and Antoine Georgesģ, 2, 4, 5 Arnold Sommerfeld Center for Theoretical Physics, Center for NanoScience, and Munich Center forQuantum Science and Technology, Ludwig-Maximilians-Universit¨at M¨unchen, 80333 Munich, Germany Center for Computational Quantum Physics, Flatiron Institute, 162 5th Avenue, New York, NY 10010, USA Coll`ege de France, 11 place Marcelin Berthelot, 75005 Paris, France Centre de Physique Th´eorique, CNRS, Ecole Polytechnique, IP Paris, 91128 Palaiseau, France Department of Quantum Matter Physics, University of Geneva, 1211 Geneva 4, Switzerland (Dated: January 2, 2020)The crossover from fluctuating atomic constituents to a collective state as one lowers temperatureor energy is at the heart of the dynamical mean-field theory description of the solid state. SStrongly Correlated Materials from a Numerical Renormalization Group Perspective:How the Fermi-Liquid State of Sr RuO Emergesįabian B. We extract quasiparticle interaction parameters from the low-energy spectrum and find an effective attraction in the spin-triplet sector. ![]() 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 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. ![]() The renormalization group flow from high to arbitrarily small energy scales clearly reveals the emergence of the Fermi-liquid state of Sr We demonstrate that the numerical renormalization group is a viable tool to monitor this crossover in a real-materials setting. 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.
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