Effect of an external magnetic field on the nematic-isotropic phase transition in mesogenic systems of uniaxial and biaxial molecules: a Monte Carlo study.
We determine the nematic-isotropic coexistence curve terminating at the critical point in a temperature-external field phase diagram for nematic liquid crystals with positive diamagnetic anisotropy, where the molecules are either perfectly uniaxial or biaxial using computer simulation of a lattice model. The coexistence curve is much steeper than that predicted by the standard Landau-de Gennes and Maier-Saupe mean-field theories. For the uniaxial system the critical magnetic field is estimated to be one order of magnitude lower than the mean-field estimate but of the same order of magnitude as the experimental measurement. Our study shows that molecular biaxiality could reduce the critical field strength significantly.
Department of Physics, Mahishadal Raj College, Mahishadal, Purba-Medinipur, West Bengal, India.
Nababrata
N
Ghoshal
Department of Physics, Sundarban Mahavidyalaya, Kakdwip, South 24 Parganas, West Bengal, India.
Kisor
K
Mukhopadhyay
Department of Physics, Jadavpur University, Kolkata 700 032, India.
Soumen Kumar
SK
Roy