Effective interactions and melting of a one dimensional defect lattice within a two-dimensional confined colloidal solid

We report Monte Carlo studies of a two-dimensional soft colloidal crystal confined in a strip geometry by parallel walls. The wall-particle interaction has corrugations along the length of the strip. Compressing the crystal by decreasing the distance between the walls induces a structural transition characterized by the sudden appearance of a one-dimensional array of extended defects each of which span several lattice parameters, a "soliton staircase". We obtain the effective interaction between these defects. A Lindemann criterion shows that the reduction of dimensionality causes a finite periodic chain of these defects to readily melt as the temperature is raised. We discuss possible experimental realizations and speculate on potential applications.