Gapless Fermions - from Fermi liquids to strange metals

This winter school was in some ways a pioneering effort for the organisers, who had thus far mainly been involved in either shorter formats, or more extended versions of schools.

Its aim was to bring students from all over the world up to the cutting edge of research into, essentially, metals of various types. The students, numbering about 45 in total, were selected from a large pool of applicants. We were somewhat, but luckily not massively, oversubscribed.

The first week had two points of emphasis. One was the experimental situation, where the speakers were asked to give an introduction to their methods as well as their most salient results. These talks turned out very different in character, playing to the various strengths of the speakers. Joe Checkelsky was extremely engaging, Amalia Coldea provided copious experimental results, and Veronika Sunko had prepared an excellent introduction to ARPES specifically for this occasion.

The other can be described as the past (R. Shankar), present (I. Herbut) and future (S.-S. Lee) of metallic theories. Again, these talks were all excellent in their own ways, and were attended even by established experts in the field.

The second week again had a number of broad overview (M. Vojta on Kondo etc; J. Schmalian on transport), as well as targeted presentations (e.g. W. Metzner on FRG, and an outstanding presentation by A. Georges on DMFT or by Th. Giarmarchi on bosonisation).

It was a pleasure to see how various topics were treated by the different speakers in often complementary ways.

On a broader note, we found attendance was an issue initially, and we had to exert some pressure to stop students from disappearing from the less prominently named talks.

We found that speakers were happy to stay for several days, which made for a wonderful and stimulating atmosphere.