Rinto Anugraha

Control parameter dependence of spatial domain structures in soft-mode turbulence

Soft-mode turbulence (SMT) is a spatiotemporal chaos in electrohydrodynamic convective systems. It is caused by a nonlinear interaction between the convection mode and a Nambu–Goldstone mode, and b...

Magnetic Field Dependence of Spatiotemporal Chaos in a Homeotropic Nematic System

We investigate the response of electroconvective patterns to an external magnetic field H in a homeotropic nematic system where spatiotemporal chaos called soft-mode turbulence (SMT) occurs. The pattern ordering M p , which shows pattern regularity in SMT, increases with the magnetic field H due to the suppression of the azimuthal rotational freedom. Three regions in the H -dependence of M p are found: the zero regime, the steep increase regime and the saturated regime. In the steep increase regime, M p shows a linear relation with \bar H 2 , from which the susceptibility χ p for the pattern ordering is obtained.

A transition to spatiotemporal chaos under a symmetry breaking in a homeotropic nematic system

This Letter reports a transition to spatiotemporal chaos (STC) in an electroconvective system of a homeotropic nematic liquid crystal under a symmetry breaking. The homeotropic system has a continuous symmetry which leads to the occurring of STC at a threshold for convection. When the symmetry is broken by an external field, a periodic pattern appears first and then STC appears at a higher transition point. The transition from the periodic pattern to STC is investigated by order parameters which were obtained from spectra of convective patterns. The results are compared with the recent theoretical researches for the damped Nikolaevskiy equation.

New measure of chaos of convective pattern in soft-mode turbulence

We investigate the response of electroconvective patterns to an external magnetic field H in a homeotropic nematic system where spatiotemporal chaos called the soft‐mode turbulence (SMT) occurs. We introduce new order parameter Op, obtained directly from the amplitude spectrum of the patterns. We measure the degree of regularity of patterns under influence of H using Op and compare with the pattern ordering Mp obtained from analogy with the magnetization in 2D XY model. Our new order parameter Op is well proportional to Mp.