Localized Andreev edge states in HgTe quantum wells
  We investigate the interplay of superconductivity and the topological order in the topological insulator (TI) formed in HgTe-CdTe quantum wells coupled to the s-wave isotropic superconductor (SC) placed on top of CdTe layer. Proximity effect induces superconducting correlations in TI effecting classification of the TI electronic states. Depending on the strength of the coupling and the initial chemical potentials in SC and TI, the edge states either (i) become gapped, or (ii) hybridize into localized Andreev states, or else (iii) merge with the bulk states turning the TI into an anisotropic narrow-gap semiconductor. 
I.M. Khaymovich, N.M. Chtchelkatchev, and V.M. Vinokur
cond-mat.supr-con cond-mat.mes-hall