Full transmission within a wide energy range and super-criticality in   relativistic barrier scattering
  For potential barriers with scalar and vector coupling, we show that a Dirac particle could experience nearly full transmission within a wide sub-barrier energy band. Moreover, for certain potential configurations, including pseudo-spin symmetry where the scalar potential is the negative of the vector, full transmission occurs for arbitrarily small momentum. 
A. D. Alhaidari, H. Bahlouli, Y. Benabderahmane, and A. Jellal
quant-ph cond-mat.mes-hall