Autumn School on Correlated Electrons, 18-22 September 2023, Forschungszentrum Jülich

Autumn School on Correlated Electrons:
Orbital Physics in Correlated Matter

18-22 September 2023, Forschungszentrum Jülich

Deadline for registrations: 31 May 2023

For more information: https://www.cond-mat.de/events/correl23

Registration page: https://www.cond-mat.de/events/correl23/register.php

Scope

In a classic paper 50 years ago, Kugel and Khomskii demonstrated that in strongly-correlated systems orbital ordering can arise from a purely electronic super-exchange mechanism and not just the conventional co-operative Jahn-Teller effect. This work opened the field of orbital physics — a field which, since then, is undergoing continuous growth. It was understood that, beside orbital ordering, super-exchange can give rise to the orbital analogue of spin-liquid states. It was shown that the directional character of the orbitals can introduce anisotropic super-exchange interactions, which, in a simplified setting, are described by compass models, a prototype for the Kitaev model. This opened new avenues of its own. More surprising phenomena arise from the entanglement of spin and orbital degrees of freedom. New developments aim at dynamically tuning orbital occupations by pushing the system out of equilibrium, and at orbital-controlled electronics.

The goal of this year’s school is to provide students with an overview of the state-of-the art in the field of orbital physics in strongly correlated systems and the techniques used to investigate them. After introducing fundamental models and effects, lectures will focus on these effects in real materials, with introductions to crystallography and symmetries, methods for building minimal tight-binding Hamiltonians, the Jahn-Teller effect, and Coulomb-enhancements of the Jahn-Teller effect. Advanced lectures will address orbital ordering, orbital liquids and Kitaev materials, as well as theoretical approaches, from self-interaction corrected density functionals to dynamical mean-field theory and beyond. Experimental lectures will present probes of spin, orbital, and charge degrees of freedom, techniques to image orbitals and orbital ordering, as well as orbitally-controlled transport phenomena.

Lecturers

• Bernard Amadon, CEA, Université Paris-Saclay
• Eva Benckiser, MPI-FKF Stuttgart
• Arnout Ceulemans, Universiteit Leuven
• Jak Chakhalian, Rutgers University
• Robert Eder, Karlsruhe Institute of Technology
• Andreas Grüneis, TU Wien
• Erik Koch, Forschungszentrum Jülich
• Nicola Lanata, Rochester Institute of Technology
• Alexander Lichtenstein, Universität Hamburg
• Takashi Mizokawa, Waseda University
• Andrzej Oleś, Jagiellonian University, Krakow
• Eva Pavarini, Forschungszentrum Jülich
• Mark Pederson, University of Texas at El Paso
• Hao Tjeng, MPI-PKS Dresden
• Simon Trebst, Universität zu Köln
• Jeroen van den Brink, IFW Dresden
• Matthias Vojta, TU Dresden

Lecture notes will be published as a book, which will be provided to every participant at the beginning of the school.

Organizers

• Eva Pavarini
  Forschungszentrum Jülich
• Erik Koch
  Forschungszentrum Jülich