Preface: phys. stat. sol. (b) 245/2
Authors: Haug Rolf 
Published: January 2008

AbstractThis special issue of physica status solidi (b) on “Quantum Hall Systems” contains a series of articles covering various aspects of quantum Hall physics ranging from the basic understanding of magnetotransport in two‐dimensional systems to theoretical and experimental works dealing with the fractional quantum Hall effect. All of these articles have been written by scientists who had participated in the Priority Programme SPP 1092 on “Quantum Hall Systems” funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG).The quantum Hall effect was discovered by Klaus von Klitzing in 1980 when he astonishingly observed plateaus in the Hall resistance of a two‐dimensional electron gas in a transistor. Nobel prizes were already twice awarded for works dealing with quantum Hall systems, 1985 to Klaus von Klitzing for the discovery of the quantum Hall effect and 1998 to Robert B. Laughlin, Daniel C. Tsui and Horst L. Störmer for the fractional quantum Hall effect. Although it is more than 25 years that the quantum Hall effect was seen for the first time, this field of research is still extremely active and fascinating due to the many unsolved questions and the steady appearance of unforeseen new phenomena, i.e. very recently quantum Hall effect in single‐ and bilayers of graphene.This issue covers a number of aspects. It starts with magnetotransport effects being observed in two‐dimensional systems of simple or more complicated geometries. Like in most of the other parts of this issue this first part consists of articles covering more the experimental aspects as well as of articles covering more the theoretical aspects. The second part entitled “Magnetization and dynamics in the integer quantum Hall effect” contains articles describing special measurement methods and their results whereas the third part deals with the physics of edge states and narrow quantum Hall systems. The last part covers several aspects of the fractional quantum Hall effect. So, these different parts show the broad range of different phenomena involved in quantum Hall physics.The Priority Programme SPP 1092 has been instrumental in bringing together the various groups in Germany working in the field of quantum Hall physics. It was funded by the German Research Foundation in the six‐year period from 2000 to 2006. The funding was provided not only for more than 70 biennial research projects, but also for workshops and symposia. The twelve workshops, colloquia and symposia organised and funded by the programme helped on one side to bind together the group of scientists fascinated by the quantum Hall effect in Germany, but on the other side they also helped to show this activity to the international physics community and to place Germany at the forefront of works in the quantum Hall effect. As a direct outcome of the funding by the Priority Programme several hundreds of scientific papers were published, a large part of them in the top journals. But the programme was also successful in helping young people in their scientific careers. About 50 Ph.D. theses have been completed and 10 young researchers working within the projects of the Priority Programme were offered professorships which they finally accepted. In the name of all who have benefited from this Priority Programme we would like to thank the German Research Foundation for this important support of our work. We thank the people of the DFG, especially Dr. Klaus Wehrberger, but also Dr. K. Zach and Dr. M. Kleinschmidt who helped in getting started and who administered the programme.
We are particularly grateful to the members of the International Peer Review Committee for their time, effort and advice which they invested into the programme. They helped to make Priority Programme SPP 1092 a successful programme.Hannover, December 2007