DISLOCATIONS AS FLEXIBLE OBJECTS - INTERACTIONS AND UNBINDING TRANSITION

The elastic interactions between dislocations in a finite lamellar sys tem of N layers are calculated as a function of the size of the system , surface tension and lamellar elastic constants. For large surface te nsion the in-plane interactions are repulsive for like dislocations an d attractive for opposite ones, decaying exponentially with the decay length proportional to square-root N. Their strength is inversely prop ortional to square-root N. For small surface tension the elastic inter actions are attractive at large distances for like dislocations and re pulsive for opposite ones. In thin films with small surface tension li ke dislocations are stabilized at finite separations (approximately sq uare-root N), while in thick films they unbind due to Helfrich forces. The unbinding transition is extremely sensitive to the surface tensio n and surface bending elastic constant.