DATES

October 23-27, 2023

DIRECTORS

• Sebastien Burdin (University of Bordeaux, France)
• Peter Hirschfeld (University of Florida, USA)
• Sergio Magalhaes (Federal University of Rio Grande do Sul, Brazil)
• Pascoal Pagliuso (University of Campinas, Brazil)
• Gertrud Zwicknagl (Technical University of Braunschweig, Germany)

OVERVIEW

Fermi surfaces and electronic band structures paradigm occupy a central place in solid state science, since most of the physical properties of bulk metallic materials are governed by conduction electrons. The underlying hypothesis, which relies on a Bloch wave description of crystalline non-interacting electronic systems, is obviously not satisfied in numerous examples of emergent materials. The most challenging examples include strongly correlated electronic systems and structurally disordered materials showing spectacular macroscopic properties related with unconventional quantum order. Despite the inapplicability of the most common approaches to calculating electronic structure, the notion of electronic bands may often be generalized to describe most of these emergent materials. A standard example of such extension, from a phenomenological point of view, is the Fermi Liquid description of strongly correlated systems: despite strong interactions, low energy excitations can usually be described as the one of a non-interacting Fermi gas with renormalized effective mass. Experimentally, a large variety of techniques have also been developed initially from a Bloch wave description of electronic matter, including ARPES, quantum oscillations, Raman, X-ray or neutron scattering spectroscopies.

The present workshop aims at the experimental and theoretical studies of emergent materials such as heavy fermions, topological insulators, high temperature superconductors, or frustrated quantum magnets. The last decades have witnessed a flurry of activities in extending the frontiers of validity of the electronic band structure paradigm for describing and characterizing strongly correlated or disordered electron systems with unconventional phases. For example, modern mean-fields techniques have been developed to derive emergent effective non-interacting band models from strongly interacting systems. In order to model some spectroscopy experiments as well as thermodynamics and transport properties of emergent materials, localized magnetic degrees of freedom may be phenomenologically either fractionalized and included into an effective Fermisurface, or considered as bosonic/classical fields coupled to a Fermi liquid. For quantitative matching with experimental measurements, very powerful techniques have been developed, improving density functional theory methods in order to take into account relevant strong correlation effects, possible conventional and unconventional orderings, as well as time dependencies.

MAIN TOPICS

• Novel materials and experimental methods, including general material elaboration and characterizations and experimental techniques for description of electronic properties: Angle Resolved Photoemission (ARPES), tunnel spectroscopies, and quantum oscillations (Shubnikov de Haas, de Hassvan Alphen); for studying electronic and magnetic correlations: electronic Raman, resonant inelastic X-ray spectroscopy (RIXS), infrared conductivity, inelastic neutron scattering (INS), nuclear magnetic resonance (NMR), muon spin resonance (μSR), x-ray and neutron diffraction; for phase transition, nonFermi-liquid and symmetry characterizations: thermodynamic and transport measurements;
• Novel numerical methods, particularly those related to the necessary improvements of Density Functional Theory methods that are required for an ab initio description of materials forming strongly correlated ground states;
• Novel analytical methods, that are required for the characterization of new quantum phases and phenomena such as unconventional superconductivity, spin-liquid phases and non-Fermi liquid behaviors, topological orders; and for an appropriate description of elementary local or collective excitations in these materials;
• Unconventional superconductivity and its interplay with magnetism, spin-orbit coupling, charge fluctuation, charge ordering in various materials;
• Emergence of pseudogaps, topology, quantum criticality and their possible connections with exotic quantum orders in real materials;
• Quantum magnetism and frustration in crystalline materials;
• Dual descriptions of emergent quantum orders in real materials. Interplay between conduction electrons and local quantum objects: multipoles, vortices, skyrmions, etc…
• Interplay between disorder and correlations in real materials, in particular those where doping with foreign element is used to tune the nature of the ground state; disorder effects resulting from the method of synthesis (powder versus single crystals, dislocations);
• Highly excited states in materials, correlated electrons far from equilibrium, and light-matter interaction in correlated electron systems.

CONTACT