Instabilities of micro-phase separated Coulombic systems in constant electric fields

TL;DR

This paper investigates the stability of lamellar phases in Coulombic systems under uniform electric fields, revealing instabilities and potential for dynamic stabilization through oscillating fields.

Contribution

It provides a detailed analysis of how electric fields affect the stability of micro-phase separated Coulombic systems, including the effects of field orientation and oscillations.

Findings

Perpendicular fields cause long wavelength instabilities.

Parallel fields produce deformed but stable interfaces.

Oscillating fields may dynamically stabilize structures.

Abstract

Mixtures of near-symmetric oppositely charged components with strong attractive short range interactions exhibit ordered lamellar phases at low temperatures. In the strong segregation limit the state of these systems can be described by the location of the interfaces between the components. It has previously been shown that these systems are stable against small deformations of the interfaces. We examine their stability in the presence of a uniform electric field. When the field is perpendicular to the lamellae, the system is unstable against long wavelength deformations for all non-zero values of the external field. A field parallel to the lamellae produces deformed but persistent interfaces. In a finite thickness system, onset of an external perpendicular field modifies the ground state. Flow between the old and new ground states requires the destruction of the original interfaces; this destruction proceeds through the instabilities identified in the bulk case. We examine the possibility of dynamical stabilization of structures by means of oscillating fields.