中国物理B ›› 2003, Vol. 12 ›› Issue (11): 1283-1290.doi: 10.1088/1009-1963/12/11/317

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First-order Fréedericksz transition at the threshold point for weak anchoring nematic liquid crystal cell under external electric and magnetic fields

关荣华1, 杨国琛2   

  1. (1)Department of Applied Physics, North China Electric Power University, Baoding 071003, China; Institute of Material Physics, Hebei University of Technology, Tianjin 300130, China; (2)Institute of Material Physics, Hebei University of Technology, Tianjin 300130, China
  • 收稿日期:2003-06-20 修回日期:2003-08-18 出版日期:2003-11-16 发布日期:2005-03-16

First-order Fréedericksz transition at the threshold point for weak anchoring nematic liquid crystal cell under external electric and magnetic fields

Guan Rong-Hua (关荣华)ab, Yang Guo-Chen (杨国琛)b   

  1. a Department of Applied Physics, North China Electric Power University, Baoding 071003, China; b Institute of Material Physics, Hebei University of Technology, Tianjin 300130, China
  • Received:2003-06-20 Revised:2003-08-18 Online:2003-11-16 Published:2005-03-16

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摘要： Based on the modified formula of Rapini-Papoular, the equilibrium equation and boundary condition of the director have been obtained and the behaviour of the Fréedericksz transition at the threshold point has been studied for weak-anchoring nematic liquid crystal cells under external electric and magnetic fields with the methods of analytical derivation and numerical calculation. The results show that, except for the usual second-order transition, the first-order Fréedericksz transition can also be induced by a suitable surface anchoring technique for the liquid crystal cell given in the paper. The conditions for the existence of the first-order Fréedericksz transition are obtained. They are related to the material elastic coefficient k_{11}, k_{33} the thickness of the liquid crystal cell, the external electric field and the strength of surface anchoring, etc.

Abstract: Based on the modified formula of Rapini-Papoular, the equilibrium equation and boundary condition of the director have been obtained and the behaviour of the Fréedericksz transition at the threshold point has been studied for weak-anchoring nematic liquid crystal cells under external electric and magnetic fields with the methods of analytical derivation and numerical calculation. The results show that, except for the usual second-order transition, the first-order Fréedericksz transition can also be induced by a suitable surface anchoring technique for the liquid crystal cell given in the paper. The conditions for the existence of the first-order Fréedericksz transition are obtained. They are related to the material elastic coefficient $k_{11}$, $k_{33}$ the thickness of the liquid crystal cell, the external electric field and the strength of surface anchoring, etc.

Key words: weak anchoring, threshold point, first-order Fréedericksz transition, electric and magnetic fields

中图分类号:  (Surface phenomena: alignment, anchoring, anchoring transitions, surface-induced layering, surface-induced ordering, wetting, prewetting transitions, and wetting transitions)

  • 61.30.Hn
61.30.Gd (Orientational order of liquid crystals; electric and magnetic field effects on order)