Realizing attractive interacting topological surface fermions: A resonating TI- thin film hybrid platform

Here we put forward a practical way to realize topological surface Dirac fermions with tunable attractive interaction between them. The approach involves coating the surface of a topological insulator with a thin film metal and utilizing the strong-electron phonon coupling in the metal to induce interaction between the surface fermions. We found that for a given TI and thin film, the attractive interaction between the surface fermions can be maximally enhanced when the Dirac point of the TI surface resonates with one of the quasi-2D quantum-well bands of the thin film. This effect can be considered to be an example of 'quantum-well resonance'. We also demonstrate that the superconductivity of the resonating surface fermions can be further enhanced by choosing a strongly interacting thin film metal or by tuning the spin-orbit coupling of the TI. This TI-thin film hybrid configuration holds promise for applications in Majorana-based quantum computations and for the study of quantum critical physics of strongly attractively interacting surface topological matter with emergent supersymmetry.