Regensburg 2019 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 17: Poster Session I
CPP 17.3: Poster
Montag, 1. April 2019, 17:30–19:30, Poster B1
Modeling the interaction of magnetically capped colloidal particles — •Maximilian Neumann1, Sibylle Gemming1,2, Gabi Steinbach2, and Artur Erbe1 — 1Institute of Physics, TU Chemnitz, D-09107 Chemnitz — 2Helmholtz-Zentrum Dresden - Rossendort, D-01328 Dresden
Colloidal self-assembly bears significant potential for the bottom-up fabrication of advanced materials and micromechanical structures. A wide range of particles with different types of anisotropy have been recognized as promising precursors for controlled structure engineering. Here, we concentrate on particles that interact via polar fields, which are intrinsically anisotropic. More specifically, we focus on the assembly of micron-sized silica spheres which are partly covered by a thin ferromagnetic layer with an out-of-plane magnetic anisotropy. To study assemblies of such magnetic particles, we introduce a simple two-parameter model: The extended magnetization distribution is approximated by a current-carrying coil enclosed inside a hard sphere. The far field of that current reproduces the stray field of a point dipole model, the near field reflects an extended magnetization. Such a model employs only two parameters to describe the shape of the magnetization distribution: The radius and the position of the coil inside the sphere. We present stable assemblies as a function of both parameters. In the limit of very small coils the analytical solution for two particles with shifted point dipoles is correctly reproduced. By increasing the radius of the coil, we reproduce experimentally observed particle arrangements not covered by models based on single shifted dipoles.