Biaxial coherence length in a nematic π-cell

In a highly frustrated calamitic nematic phase, the strain can be relaxed by lowering the nematic order: the starting uniaxial symmetry can be broken and it can be replaced locally with transient biaxial domains. Using simple optical retardation measurements, we estimate the length scale over which the biaxial disturbance decays in space within a pi-cell submitted to a weak electric field. We also characterise the transition cascade from the uniaxial splay texture to a bend texture through slow defect motion.