Backward Tamm states in left-handed metamaterials
  We study the electromagnetic surface waves localized at an interface separating a one-dimensional photonic crystal and left-handed metamaterial, the so-called surface Tamm states. We demonstrate that the metamaterial allows for a flexible control of the dispersion properties of surface states, and can support the Tamm states with a backward energy flow and a vortex-like structure. 
Abdolrahman Namdar, Ilya V. Shadrivov, and Yuri S. Kivshar