Electromigration-induced breakup of two-dimensional voids

The motion and shape evolution of a void in a two-dimensional current carrying conductor is studied numerically. A circular void is linearly stable, but becomes unstable beyond a finite threshold deformation amplitude which decreases with increasing void radius. If the void is initially elongated along the current direction it expels small, stable daughter voids, while for elongations perpendicular to the current an invagination occurs which splits the void in two. The behavior near threshold is linked to the non-normality of the eigenmodes of the linearized problem. Perfectly circular voids can also be destabilized by their mutual long-ranged electromagnetic interaction. [S0031-9007(98)05418-0].