Dynamics of a sheared twist-bend nematic liquid crystal

Abstract

We study the flow behavior of a twist-bend nematic (NTB) liquid crystal. It shows three dynamic regimes in certain temperature and shear-rate range. In region I, σ∼γ˙, in region II, the stress shows a near plateau, characterized by a power law σ∼γ˙α, where α∼0.1-0.4 and in region III, σ∼γ˙. With increasing shear rate, σ changes continuously from region I to II, whereas it changes discontinuously with a hysteresis from region II to III. In the near plateau (region II), we observe dynamic stress fluctuations, exhibiting regular, periodic, and quasiperiodic oscillations under the application of a steady shear. The observed spatiotemporal dynamics are close to those predicted theoretically in sheared nematogenic fluids.