INTAS-NETWORK Project No 03-514778
WORKSHOP 20004

"Hierarchy of scales in magnetic nanostructures"

Summary

The aim of the project is to investigate the low-dimensional magnetism at different spatial and temporal length scales, and to track the evolution of fundamental magnetic interactions versus observation scale and to develop routes for formation of artificial nanostructures with unique magnetic properties.

We will study non-collinear spin structures in magnetically ordered small supported clusters at the smallest obtainable length scale and investigate strong correlations, responsible for the Kondo-like resonance at low temperature.
At the next length scale, we will develop advanced technology of multilayer growth with extremely low interface roughness. Various complimentary experimental methods will be applied for the characterization of samples, available to the teams participating in the project.
The interpretation of experimental data and the theoretical reconstruction of atomic-scale interface structures will be performed by using modeling of sample growth and subsequent self-consistent calculations of magnetic moments on each atom using various ab-initio and real space Hamiltonian approaches.

Growth of the multilayers with thin magnetic layers and very flat interfaces will allow us to grow superlattices, where the transition from three-dimensional (3D) to two-dimensional (2D) magnetism can be experimentally realized. Such a transition will be achieved by manipulation of the interlayer exchange coupling with hydrogen loading. The dependence of the Curie temperature for the individual ferromagnetic layers as a function of the sign and strength of the interlayer exchange coupling will give unique information about phase transition in 3D, 2D and intermediate dimensionality.

Ordered arrays of ferromagnetic nanoparticles and quantum dots with different lateral size and with various distances between dots will be fabricated on metal surface. The influence of interaction between particles on their collective magnetic behaviour will be studied using complimentary experimental methods. Exploring the influence of the exchange coupling and finite size effects on magnetic phase transitions will be performed in extended films and patterned magnetic structures. Experiments will be complemented with calculations of magnetic structure as well as micro-magnetic modeling.

The integration of the research activities of the group members, which already exists between some of the group, will create a more concerted approach to tackle the most challenging problems in low dimensional magnetism by making a better and more cost-effective use of resources.

Participants

1. Uppsala University, Department of Physics, Uppsala, Sweden.
   (Prof. Bjorgvin Hjorvarsson, co-ordinator)
2. St.Petersburg State University, ICAPE, St.Petersburg, Russia.
   (Prof. Valery Uzdin, co-ordinator from Russian side)
3. Ruhr-University Bochum, Department of Physics and Astronomie, Bochum, Germany.
   (Prof. Hartmut Zabel)
4. Russian Federal Nuclear Center - VNIIEF, Sarov, Russia
   (Dr. Yurij Kudasov)
5. CNRS, Institut Physique et Chimie des Materiaux, Strasbourg, France.
   (Dr. Claude Demangeat)
6. Institute for Physics of Microstructures , Nizhnij Novgorod, Russia
   (Prof. Andrej Fraerman)
7. University Duisburg-Essen, Duisburg, Germany.
   (Prof. Werner Keune)
8. Physical-Technical Institute of Ural Branch of Russian Academy of Sciences, Udmurtian State University, Izhevsk, Russia.
   (Prof. Anatoly Arzhnikov)
9. University of Valladolid, Valladolid, Spain
   (Prof. Andreas Vega)
10. Joint Institute for Nuclear Research, Frank Laboratory of Neutron Physics, Dubna, Moscow Region, Russia.
    (Prof. Viktor Aksenov)