11 research outputs found
Magneto-optic dynamics in a ferromagnetic nematic liquid crystal
We investigate dynamic magneto-optic effects in a ferromagnetic nematic
liquid crystal experimentally and theoretically. Experimentally we measure the
magnetization and the phase difference of the transmitted light when an
external magnetic field is applied. As a model we study the coupled dynamics of
the magnetization, M, and the director field, n, associated with the liquid
crystalline orientational order. We demonstrate that the experimentally studied
macroscopic dynamic behavior reveals the importance of a dynamic cross-coupling
between M and n. The experimental data are used to extract the value of the
dissipative cross-coupling coefficient. We also make concrete predictions about
how reversible cross-coupling terms between the magnetization and the director
could be detected experimentally by measurements of the transmitted light
intensity as well as by analyzing the azimuthal angle of the magnetization and
the director out of the plane spanned by the anchoring axis and the external
magnetic field. We derive the eigenmodes of the coupled system and study their
relaxation rates. We show that in the usual experimental set-up used for
measuring the relaxation rates of the splay-bend or twist-bend eigenmodes of a
nematic liquid crystal one expects for a ferromagnetic nematic liquid crystal a
mixture of at least two eigenmodes.Comment: 20 pages, 23 figures, 42 reference
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