Nr. 34 - Strongly interacting condensed matter

Approved FOM programme

Objectives

This research programme focuses on strongly-interacting condensed matter physics through active collaboration between theoreticians and experimentalists. The emphasis will be on new basic questions and concepts which overlap with, and have possible implications for, other fields of physics.

Background, relevance and implementation

Since the birth of quantum mechanics, solid state physics has grown into an active field of research because of its intellectual challenge and its implications for semi-conductor technology, magnetic materials and other technologies. Rapid progress has been possible because the behaviour of simple metals and semiconductors can be described in relatively simple terms based on the notion of independent quasi particles. This means that although the parameters which describe the electronic behaviour quantitatively depend on the particular material, the qualitative behaviour remains essentially unchanged: the electrons and holes behave as almost free, non-interacting fermions.
The theoretical basis for this so-called Landau-Fermi liquid scenario was developed mainly in the 1950s and 1960s. Over the past decade, however, it has become clear that these standard notions break down for many new materials. A new theoretical framework, together with new ways of analysing data and probing experimental systems, are required. Collaboration between theoreticians and experimentalists covering a broad range of interests is essential as the phenomena and techniques encountered range across composite fermions; many-particle states with bosonic character; competition between superconductivity and (anti)ferromagnetism; competition between localisation and electron interactions; glassy behaviour; and quasi-one-dimensional behaviour.