Giant nonlinearity in zero-gap semiconductor superlattices

Using an effective medium approach, we describe how, by combining mercury-cadmium-telluride semiconductor alloys with band gap energies of opposite signs, it may be possible to design a superlattice where the electrons have isotropic zero-effective mass and a single valley linear energy-momentum dispersion. We demonstrate that, because of the zero-mass property, the superlattice may have a strong nonlinear optical response.