8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P5.84Wed 711:10-14:00Suspensions of particles with shifted magnetic dipolesSofia Kantorovich, 1 Rudolf Weeber, 1 Marco Klinkigt, 1 and Christian Holm 11 Institute for Computational Physics, University of Stuttgart, Pfaffenwaldring, 27, 70569,Stuttgart, GermanyIn a previous study we investigated the ground state for systems of particles, the magnetic momentof which was shifted from the centre of particle, and pointed always outwards radially, using thecombination of Monte Carlo simulations and analytical calculations. The shift influences greatlythe microstructure at low temperatures [1] The model of shifted dipoles was able to reproduced theexperimentally observed “magic number clusters” [2]. The behavior of a suspension of particleswith shifted magnetic dipoles in the presence of an external magnetic field at room temperaturesboth in quasi-two dimensions and in the bulk is strongly influenced by the shift factor. To understandthe microscopic properties of our system better, we are developing new methods to analyzethe clusters which magnetic particles form for different shift values. In the present work we developthe algorithm which allows for the presence of antiparallel pairs and triangular conformations.Currently, analytical calculations are performed in order to obtain magnetization curves fordifferent shifts using perturbation theory in both 2 and 3 dimensions. We also work on the clusterformation theory. The tunable anisotropy of such a system will allow to control the process ofcluster formation at room temperatures and crystallization at low temperatures.References[1] S. Kantorovich, R. Weeber, J. Cerda, C. Holm, Soft Matter, DOI: 10. 1039 / C1SM05186E(2011)[2] L. Baraban, D. Makarov, M. Albrecht, N. Rivier, P. Leiderer and A. Erbe, Phys. Rev. E, 77,031407 (2008)[3] J. Cerda, V. Ballenegger, O. Lenz, C. Holm, J. Chem. Phys. 129, 234104 (2008)[4] A. Brodka, Chemical Physics Letters 400, 62?67 (2004)[5] H. -J. Limbach, A. Arnold, B. Mann, C. Holm, Comput. Phys. Commun. 174(9), 704 (2006)84