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L. I. Knyazeva, D. V. Makarov

Author affiliations
Perm State University,
15 Bukireva St., Perm, 614990, Russia
E-mail: dmakarov@psu.ru

Abstract
The influence of the fourth order anchoring anisotropy parameter on the orientational transitions in ferronematic liquid crystals induced by a magnetic field is studied within the continuum theory. Equations of the orientation equilibrium are solved numerically. Field dependences of the free energy of ferronematic and the angles of rotation of the director and the magnetization vector are plotted for various values of the anchoring anisotropy parameter. The types of orientation transitions implemented in the system are analyzed, and the corresponding fields of transitions between the orientational phases of ferronematic are found. The dependence of field of equilibrium transition from the angular orientation phase to the planar one on the anisotropy parameter is found numerically and the dependence of the field of transition from the homeotropic phase to the planar one is found analytically. It is determined that transitions to the planar phase are the first-order phase transitions for all values of anisotropy parameter at which the surface potential has additional minima. It is shown that with an increase of the anisotropy parameter of anchoring the critical field required for the transition of ferronematic from the homeotropic orientational phase to the planar one decreases.

Keywords: ferronematic, bistable surface potential, magnetic field, orientational transitions