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Correlated electronic states of low dimensional systems

 

Over the recent years, the interest in the physics of strong correlations has undergone a tremendous revival in many fundamental topics of condensed matter physics. The systems concerned include oxide materials (such as the superconducting compounds of high critical temperature), heavy fermions, organic materials, quantum spin systems, 2D and quasi-2D electron gases, meso- or nanoscopic objects, and the recently discovered graphene layers. Moreover, cold atoms in optical traps may be used as a physical representation of theoretical model systems, studied in the framework of correlated electron systems. The relevant parameters of these models may now be completely controlled. Considerable theoretical and experimental progress has been achieved in the understanding of the complex nature of their ground states and of their excitations. These correspond to new quantum collective states the properties of which are in stark contrast with the conventional description in terms of Landau quasiparticles, which applies generally well for 3D systems. Transport and magnetic properties in these materials often display quite unconventional features, particularly when they interact with local probes or with reservoirs. Much remains to be understood about these systems, such as the dimensional crossover associated with the emerging couplings when lowering the temperature, the role of disorder, and the competition between the different phases. Increasingly, concepts that have been used to treat a particular problem appear to describe a whole range of other correlated systems, as well. The aim of the present conference will be to highlight these aspects and to show that there is a gradual convergence towards a unified description of correlated electronic states of low dimensional systems.