Bloch Walls and Macroscopic String States in Bethe's solution of the   Heisenberg Ferromagnetic Linear Chain
  We present a calculation of the lowest excited states of the Heisenberg ferromagnet in 1-d for any wave vector. These turn out to be string solutions of Bethe's equations with a macroscopic number of particles in them. These are identified as generalized quantum Bloch wall states, and a simple physical picture provided for the same. 
Abhishek Dhar and B Sriram Shastry