We discuss a dynamical transition in the propagation of fronts into an unstable state of a bistable system. In one regime, the front leads to a new form of pattern formation, in which a periodic state consisting of kinks and antikinks emerges whose wavelength diverges at the transition with an exponent frac32;. In the particular model studied, this periodic state is actually weakly unstable.

• Received 14 December 1987

DOI:https://doi.org/10.1103/PhysRevLett.60.2641