The Frederiks effect and related phenomena in ferronematic materials
Victor, Zadorozhnii, V. I. , Tim, Sluckin, T. J, Vladimir, Reshetnyak, V. Y. and Ken, Thomas K.S. (2007) The Frederiks effect and related phenomena in ferronematic materials. Siam Journal on Applied Mathematics, 68, (6), 1688-1716.
- Published Version
Abstract. Using continuum and statistical mechanical theories, we study the switching properties of a ferronematic in a nematic liquid crystal cell subject to homeotropic boundary conditions at the cell and particle walls. An external magnetic ﬁeld normal to the cell plane is also imposed. At low ﬁelds we ﬁnd thresholdless switching of the nematic director, consistent with experimental data. At higher ﬁelds, there are three regimes, depending on the strength of the anchoring interaction between the director and the ferroparticle orientation. For low anchoring strengths, there is an inverse Frederiks eﬀect, and the nematic reorientation reduces and then disappears continuously at a critical magnetic ﬁeld. At intermediate ﬁelds, the degree of reorientation reduces at high ﬁelds but remains ﬁnite. For high ﬁelds, however, the director switching saturates. The dimensionless temperature scale in the problem involves the temperature, the mean nematic elastic constant, the colloidal density, and the cell dimension. If this quantity is suﬃciently low, then high magnetic ﬁelds can cause magnetic segregation. The segregation order parameter is coupled to the director distortion, and this can change the inverse Frederiks transition into a ﬁrst order transition, leading to bistability in an intermediate ﬁeld regime. These features are perturbed but not changed structurally by the eﬀect of a small bias magnetic ﬁeld (< 10 Oe) normal to the unperturbed director. Subject to suitable choice of parameters, the theory is also quantitatively consistent with the results of the classic experiment of Chen and Amer in 1983.
|Divisions:||Faculty of Physical and Applied Science > Electronics and Computer Science > Electronic & Software Systems
|Date Deposited:||17 Aug 2011 09:46|
|Last Modified:||02 Mar 2012 14:06|
|Contributors:||Victor, Zadorozhnii, V. I. (Author)
Tim, Sluckin, T. J (Author)
Vladimir, Reshetnyak, V. Y. (Author)
Ken, Thomas K.S. (Author)
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