Der Einfluß magnetischer Felder auf die Torsionsscherung von MBBA / Torsional Shear Flow of MBBA in Magnetic Fields

Abstract

Abstract Quantitative results are reported on the influence of a homogeneous magnetic field upon the torsional shear flow of a homeotropic layer at 22.5 °C. In subcritical fields Hx parallel to the layer, as well as in weak fields Hz normal to the layer, one gets K3/μ0 Xa = 3.76±0.2 A2 . In oblique magnetic fields (Hx , 0, Hz) one obtains (λ2-λ1)/μ0 Xa=(11.7±0.4)x1010 A2 m-2 s. In addition, a hysteresis effect in supercritical fields Hx and the formation of a long and straight magnetic wall are described. The magnetic wall becomes distorted under the action of the shear flow. Hereby a new domain can be produced which has a 180° inversion wall parallel to the boundaries of the layer.