Regensburg 2016 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 6: Colloids and Complex Fluids II (joint session BP/CPP/DY, organized by CPP)

CPP 6.10: Vortrag

Montag, 7. März 2016, 12:30–12:45, H51

Enhanced magneto-optical response in dispersions of anisometric pigment particles — •Kathrin May, Alexey Eremin, and Ralf Stannarius — Institute of Experimental Physics, Otto von Guericke University Magdeburg, Universitätsplatz 2, 39016 Magdeburg, Germany

Colloidal suspensions of anisometric particles show a variety of unique properties depending on particle concentration and external electric fields, such as the formation of ordered phases, phase separation, electro-optical effects, and non-linear rheology. Electro- and magneto-optical properties of colloids are of particular interest because of the possible applications in electrophoretic ink displays and other technologies. We demonstrate a binary colloidal system with an unusually strong magneto-optical response which is comparable with that of thermotropic liquid crystals. This system is based on a binary mixture of elongated non-magnetic pigment particles and a small volume fraction < 0.1 v/% of spherical magnetic nanoparticles. The birefringence is caused by a partial alignment of the pigment particles, controlled by anisometric agglomerates of the magnetic particles that form in a magnetic field. This effect is discussed in the frame of the Onsager-Lekkerkerker theory of sterical alignment transfer in binary mixtures of colloidal particles.

The authors acknowledge the support by DFG (SPP 1681).