Within the Landau–de Gennes phenomenological theory, we study the influence of an applied electric field with average strength $E_a$ on the position of a nematic line defect with topological charge $M=\pm \frac{1}{2}$ in a hybrid cell. We explore the biaxial structure of the defect core and we describe its expulsion from the cell upon increasing $E_a$. We show that prior to the expulsion the defect core displays dramatic changes for strong enough surface anchorings. At a critical value of $E_a$, the core broadens and merges into a surface layer with a large biaxiality. This transition corresponds to the reconstruction of the nematic order already observed in the bulk in response to an applied electric field. A similar order reconstruction could take place even in the absence of defects, but at a higher threshold.

• Received 13 November 2006

DOI:https://doi.org/10.1103/PhysRevE.75.031708