A continuum micromorphic approach to nematic liquid crystals is exploited in order to describe electro-magneto-elastic coupling effects. Nematic microdeformation is modeled by relating microinertia, electric dipole and quadrupole densities to microrotation. Accordingly, polarization and magnetization are obtained together with a constitutive law for magnetic induction. The coupled system of balance laws for linear and angular momentum and Maxwell’s equations is employed to model equilibrium for an homeotropic structure of a nematic layer subject to electric and magnetic fields, assuming strong anchoring on the layer’s boundaries. It is shown that the trivial solution of null deformation allows for a not uniform magnetic field in the presence of a not null applied electric potential. The magnetic field induced Freedericksz transition is derived obtaining a threshold value of magnetic field which depends on the electric potential. Numerical results show an hysteresis behavior of the deformation solution just behind the threshold field, which is compatible with a first order, magnetic induced transition.

Electromagnetic coupling in nematic liquid crystals modeled as microcontinua

Romeo, Maurizio
2019-01-01

Abstract

A continuum micromorphic approach to nematic liquid crystals is exploited in order to describe electro-magneto-elastic coupling effects. Nematic microdeformation is modeled by relating microinertia, electric dipole and quadrupole densities to microrotation. Accordingly, polarization and magnetization are obtained together with a constitutive law for magnetic induction. The coupled system of balance laws for linear and angular momentum and Maxwell’s equations is employed to model equilibrium for an homeotropic structure of a nematic layer subject to electric and magnetic fields, assuming strong anchoring on the layer’s boundaries. It is shown that the trivial solution of null deformation allows for a not uniform magnetic field in the presence of a not null applied electric potential. The magnetic field induced Freedericksz transition is derived obtaining a threshold value of magnetic field which depends on the electric potential. Numerical results show an hysteresis behavior of the deformation solution just behind the threshold field, which is compatible with a first order, magnetic induced transition.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11567/941308
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