Wall-wall and kink-kink interactions in ferroelastic materials

Abstract

Kinks interact with other kinks and antikinks elastically in ferroelastic domain walls and other interfaces in ferroic materials. In thin samples, suitable for transmission electron-microscopy, the interaction is purely dipolar with no indication of monopolar or higher order contributions. Kinks and antikinks attract each other while kink-kink interactions are repulsive. When the kinks are situated in two parallel twin walls, they display the same attraction/repulsion. We argue that this interaction constitutes, part or all, the elusive wall-wall interaction in ferroelastics. The dipolar interactions over distances $d$ between the kinks and between walls decay as $1/{d}^{2}$ when the samples have some nanoscale size. Nanoscale samples bend and tilt when kinks are introduced with typical bent regions of some 1 nm and tilt angles of some $1.{2}^{\ensuremath{\circ}}$. Multiple kinks will enhance the effect systematically and bent and modulated twin walls are predicted.