Third International Summer School on Strongly Correlated Systems held in Debrecen, 6–11 September 2004

Following the first 1 and the second 2 International Schools organized by the Solid State Physics Group of the Department of Theoretical Physics of the University Debrecen, the Third International Summer School on Strongly Correlated Systems was held in Debrecen, Hungary, during 6–11 September 2004.

The participation of the University of Debrecen in the European programmes has been considerably enhanced in the past few years. This brought a strong European focus for the University and signalled the year 2004 as the first year of Hungary's membership of the European Union. For example, I mention that active involvement in international programmes like Socrates, Phare, Tempus, IBRD and Eu5 have contributed to the establishment of new study tracks and curricula, and the development of postgraduate education. The University has signed bilateral agreements with 57 universities all over the world. In addition, we have been participating in exchange programmes such as CEEPUS, ISEP, ERASMUS, MCTS (Maastricht Center for Transatlantic Studies), etc. Furthermore, the University of Debrecen is a member of several organizations such as CRE, ACRU, ESMU, IAUP, and EAIE.

Within this framework, our International School was organized under the auspices of the Department of Theoretical Physics for PhD students and young researchers from the region, and has gained financial support this year from the Hungarian Academy of Sciences (MTA), from the Office of External Scientific Connections of the Hungarian Academy of Sciences (NEFIM), the Graduate School in Physics of the University of Debrecen, and the National Foundation for Scientific Research. I also acknowledge the help of the Institute of Nuclear Research in Debrecen of the Hungarian Academy of Sciences (ATOMKI) who kindly allowed us to use the ATOMKI Guest House for accommodation of the invited lecturers, the ATOMKI Dining Room for meals, and provided us with the poster boards as well. I would also like to thank the lecturers for accepting the invitations and making a major contribution to the advancement and dissemination of condensed matter physics in the region.

At the Department of Theoretical Physics of the University of Debrecen, interest in solid state physics goes back to the 1950s, when the former head of department, Rezsö Gáspár, analyzed, from the quantum chemistry and group theory point of view, the electronic structure of SeTe. Interest regarding theoretical aspects connected with condensed matter physics increased at the beginning of the 1970s, when Ágoston Bába, a member of the former teaching staff, published in the local journal Acta Univ. Debreceniensis two papers regarding single electron movement in a periodic potential. This line of research was continued in the 1980s by Gyula Bárdos, who, together with his students, investigated the effects of irradiation on solid structures, using numerical simulations. Quantum mechanical many-body aspects started to be analyzed in 1992, when the organizer of the International Summer Schools in Condensed Matter Theory at the University of Debrecen arrived at the Department of Theoretical Physics.

Concerning the programme of the present School we mention the following. On the first day, after the introduction presented by the organizer (Zsolt Gulácsi, University of Debrecen), the complex interplay of spin, charge and lattice for superconducting materials was presented (Annette Bussmann-Holder, Max Plank Institute, Stuttgart), and the theory and application of the Gutzwiller wavefunction for correlated electron systems was discussed (Florian Gebhard, Phillips University, Marburg). The second day was allocated to the Coulomb blockade and the Kondo effect in quantum dots (Gergely Zaránd, Technical University of Budapest) and ultracold atoms in optical lattices as tunable quantum many-body systems (Walter Hofstetter, RWTH Aachen). The second day ended in the late afternoon with the poster session organized for PhD students, where around ten posters were presented. On Wednesday (8 September) the dynamical mean field theory connecting quantum impurity physics to lattice problems was discussed first (Ralf Bulla, University of Augsburg), and the applications of relativistic quantum mechanics in condensed matter theory were presented in the afternoon (Balazs Gyorffy, University of Bristol). This day had the highest number of invited lecturers and as such it naturally led to the continuation of the scientific discussions even during the School banquet organized in the evening. On Thursday the subject of quantum phase transitions in correlated electron systems followed (Matthias Vojta, University of Karlsruhe), and ab initio approaches relating magneto-optical transport in solid systems with reduced dimensions (Andras Vernes, Technical University of Vienna) were discussed. The programme continued into the evening, when information regarding publication of the contributing scientific materials in Philosophical Magazine was provided. During the following day, magnetic semiconductors were presented (Mona Berciu, University of Vancouver) and the subject of econophysics as seen by physicists was discussed (Zoltan Eisler, Technical University of Budapest). On the last day, Kondo lattices were analyzed (Miklos Gulacsi, Australian National University, Canberra), and the closing ceremony gave Balazs Gyorffy (University of Bristol) the opportunity to present his impressions of the School. In his concluding remarks, he emphasized that during the lectures, of three hours duration each, a comprehensive overview of both technological and theoretical developments connected with condensed matter physics in the last few years had been presented. He provided the diplomas certifying the participation of students in the scientific events of the School, and mentioned that the scientific atmosphere of this Third International Summer School led him to feel not at the border, but at the center of the European Union.

I wish to thank everyone who helped me in organizing the School. I would especially like to thank Peter de Chatel, János Kertész, Rezsö Lovas, Dezsö Beke, Kornél Sailer, Kornél Ecsedi and Sándor Mészáros from the teaching staff. I also thank Ms. Zsuzsa Molnár, Ms. Éva Kolozsvári, and Ms. Piroska Haimhoffer who have kindly helped in all administrative problems starting from the collection of the regular mail, up to organizing the web page of the School.

With around 35 participants and 35 effective contact teaching hours activity, the Third International School on Strongly Correlated Systems was a high-level scientific event helping the scientific development in the field of condensed matter physics in the region. Like the first School in 1996 and the second School in 2000, the event was organized with the underlying aim of providing clear help in the scientific development and careers of the younger generation from this part of Europe and its surroundings. We earnestly hope that these scientific and pedagogical purposes have been clearly fulfilled.