Correlated Electrons in Transition-Metal Compounds:
New Challenges

Strongly correlated transition-metal compounds show very rich physics based on competing interactions and competing phases. The interplay of spin, charge, orbital, and lattice degrees of freedom has been viewed as the main driving force for many years. More recently, this has been complemented by investigations of the role of relativistic spin-orbit coupling, which can result in the emergence of novel phases and topological states of matter. Transition-metal compounds were the binding factor of this workshop, bringing together theoretical model Hamiltonian approaches, first principles density functional theory based calculations, spectroscopic, magnetic, transport, and structural measurements, and the synthesis of new materials. The interplay and mutual frustration of electron-electron interactions and relativistic spin-orbit coupling effects have been the main focus of this workshop held from November 5 to 9, 2018.

With 50 invited talks, this workshop attracted a large number of leading scientists from all over the world with a balanced share of theoretical and experimental physics. In total, the 97 participants from 17 countries formed a highly interacting well-focused group of senior researchers and younger scientists. In addition, the workshop profited from the attention of many further colleagues from different institutes in Dresden who complemented the audience. Many participants mentioned the striking coherence of the talks and the very inspiring atmosphere.

The four keynotes were given by Bob Cava (Princeton), Antoine Georges (Paris & New York), Yoshinori Tokura (Tokyo), and Maxim Mostovoy (Groningen). The MPI colloquium was contributed by George Sawatzky (Vancouver). Particularly noteworthy were the three very clear talks given by Judit Romhanyi (Okinawa), Alessandro Revelli (Cologne), and Oleg Janson (Dresden), three younger scientists who made excellent use of the chance to present themselves and their fascinating results. Other young colleagues were strongly involved in the lively discussions during the extended lunch break, in the coffee breaks, and after 17:00, for instance during the poster sessions. 40 posters were presented and discussed until late in the night. The Max Planck institute is the perfect place fostering such extensive discussions, laying ground for intense collaborations.

The promise held by the prominently staffed list of speakers very nicely materialized during the workshop. Both talks and posters were very well received. The latest developments in both theory and experiment were put in perspective, including in particular topics such as topological quantum spin liquids, exotic quantum states dominated by strong spin-orbit coupling, Kugel-Khomskii-type spin-orbital physics, negative charge-transfer gap compounds, multiferroics, topological defects, or Dirac and Weyl semi-metals.