Spinhenge@home carries out research in nano-technology and specialises in Molecular Magnets: Controlled Nanoscale Magnetism to make molecular magnetic materials technologically appropriable. In the future these molecules will be used in local tumor chemotherapy and to develop tiny memory-modules.
Spinhenge@home project URL; http://spin.fh-bielefeld.de/
Why study this particualr simulation?
In all industrial nations the nano-technology is being celebrated as one of the key technologies of the 21st Century. Particularly with regard to future electronics, pioneering innovations are expected. Nano-technology lives from the vision to be able to control matter specifically at the atomic level. While this is in general still a pipe-dream, these processes meanwhile attained a degree of quality which permits almost without limitation but with surprising systematic the creation of any magnetic molecules within the scope of "chemical engineering". By means of these magnetic molecules new nano-magnetic applications, as highly integrated memory modules or tiny magnetic switches will be developed in the future. Furthermore biotechnological and medical applications (e.g. local tumor chemotherapy) are aimed to achieve. In the context of this project in co-operation with the universities Osnabrück and Bielefeld and the Ames Laboratory in Ames, Iowa, USA, extensive numeric Simulationen concerning the physical characteristics of magnetic molecules are processed. Therewith the subject is especially to discover highly promising structures, who could, regarding their new characteristics serve the chemists quasi as samples to synthesize analogical new molecules. That way, recently a structure could be found, which constitutes a tiny magnetic switch (see picture).
The targeted synthesis of tailor-made magnetic molecules was long time an unrealized dream of chemists and physicists. Only in the last ten years it succeeded to develop and utilize the required processes for the production. Meanwhile these processes attained a degree of quality which permits almost without limitation but with surprising systematic the creation of any magnetic molecules within the scope of "chemical engineering".
|Metamagnetic phase transition of the |
antiferromagnetic Heisenberg icosahedron.
The icosahedron in a linearly ramped field
With the appearance of the first magnetic molecules, a completely new and unique area of research arised for the physicists. The reason for that is, above all, that the chemical structure of these molecules permits to observe and measure the magnetic characteristics of individual molecules. The physicists owe this fact the distinctive structure of the molecules:The magnetic ions are embedded into an organic matrix and and are surrounded by large ligand complexes, so that a magnetic interaction with neighbor molecules can be disabled to a large extent. That means in particular that measurements of (poly-) crystalline samples consisting of a large quantity of molecules, immediately detect the intra-molecular interactions within a molecule. This fact is particularly interesting and hardly conceivable that the produced molecules are partially highly symmetrical concerning the geometrical arrangement of the magnetic ions. Small, quasi-one-dimensional systems with two to ten iron ions are to be encountered as well as magnetic cages with more paramagnetic centers. These almost ideal "Laboratory systems" enable it to answer fundamental questions to the magnetism: Particularly systems with a small quantity of magnetic ions and small spin quantum numbers permit an accurate quantum-mechanical handling, which can be directly compared with experimental results. Beyond that the variation of size, symmetry and spin quantum number (by substitution of the ions) enables an evaluation of quantum-mecanical accurate and classical aproximated ideas of the models. Basic questions regarding the modification of magnetic characteristics with transition from the molecule to the solid state can be just as well beiing tested as technical applications in the nano and biotechnology.
The goal of this research project is to increase the basic understanding in the field of the molecular magnetism as well as to undertake a push to new application areas. In addition both theoretical and experimental investigations with teams at the Ames Laboratory and at other locations are being performed presently.
In order to take into account the increasing significance of computer science in physics, at several German universities already corresponding courses of studies ("physics with informatic") were established. The here described research projects are directed to deepen the linkage of both disciplines in research and study. The following therefore shows project-descriptions, which emphasize physics, some others focus computer science.
Slow motion of the phase transition
3. Research subjects
3.1 Spindynamic in magnetic molecules
|Results for classical simulations|
3.2 Efficient simulation methods for thermodynamic analysis at complex Spinsystems
In the research of material, In the field of molecular-dynamic simulation methods there is a series of known and new promising approaches. The experience indicated that the most efficient methods are those, which arise as a result of a combination of different techniques. These hybrid methods combine the benefits of several techniques, in order to be able to determine even more precise and faster thermodynamic characteristics. In the context of this major point of research further developments and optimizations of the existing deterministic and stochastic techniques are to performed and new techniques being developed and analyzed. Objective is to provide a collection of optimized techniques for the different problem areas. The emphasis , beside the question of physical modelling of heating bath effects, is on the side of computer-science oriented aspects: Strategies for the parallelism of techniques and new options of utilizing distributed computing are to be analyzed. As informative example the SETI@home project is mentioned.
3.3 Approximate description of complex molecular arrangements
|Video 1: Modulated spin waves and robust|
quasi-solitons in classical Heisenberg rings
3.3.1 Micro magnetism in complex structures
Micro magnetism represents a tremendous important and challenging scope within "the Computational Physics". In the context of this area of research methods are to be established in order to analyze static and dynamic micro-magnetic phenomena. Both, on the part of the basic research and from applied side (keyword: Magneto-electronics) a large interest exists in the forecast of magnetic structures (e.g. domain walls) as well as in the dynamic investigation of magnetic resetting processes. The theory of the micro magnetism represents an important link between processes on atomic scale and mesoskopic and macroscopic phenomena.
3.3.2 Visualization of Spindynamik-Simulations
The scope of the ongoing assignments exposed, that the visualization of static and dynamic results crucially contributes to the understanding of the basic physics trials. So for example three-dimensional representations of the spin arrangements could supply knowledge over "the basic state" of magnetic molecules. In order to examine the dynamics of domain-walls at a model, the visualization is an indispensable tool to analyze micro-magnetism. In addition an entire set of descriptive diagrams and animations for the principles of the magnetism by means of already existing visualization routines could be generated. The techniques used so far are not very effective, however on the other hand a whole string of methods about the visualization of three-dimensional data-sets can be found in the literature, which are to be examined and used for these purposes. Besides the aspects of research in particular results for the support of lectures and practical courses can be found. Suitable "tools" e.g. in the scope of a "simulation practical course" could be applied.
3.4 Investigations to Quantum-Informatics
|Video 2: Modulated spin waves and robust|
quasi-solitons in classical Heisenberg rings
Over all this fascinating complex of themes covers fundamental research, both in the area of physics and computer science, however likewise provide a spectacular utilization of magnetic molecules. Both, theoretical and experimental assignments provide a doorway to this area of research.
4. Procedure and work schedule
As starting point a fully functioning and easy to use application is already available. That allows to continue existing projects and to begin new projects in all areas of research as specified above. The described questioning allows to extract diploma and doctoral theses with varying degrees of difficulty, that for students of all courses of studies attractive possibilities of cooperation can be offered. In particular areas were computer-science is defined as a main topic, latest methods and techniques of System- and Software development will be used. The presented research topics are thematically and technically closely related. The goal is, to set-up a structured "knowledge-database" utilizing the respective physical, methodical and technical findings of each research topic in order to guarantee, that appropriate knowledge is being transferred and not lost due to the departure of staff members.
5. International co-operation
|Video 3: Modulated spin waves and robust|
quasi-solitons in classical Heisenberg rings
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