Domain walls in three-field models
  We investigate the presence of domain walls in models described by three real scalar fields. We search for stable defect structures which minimize the energy of the static field configurations. We work out explict orbits in field space and find several analytical solutions in all BPS sectors, some of them presenting internal structure such as the appearence of defects inside defects. We point out explicit applications in high energy physics, and in other branches of nonlinear science. 
D. Bazeia, L. Losano, C. Wotzasek