Polarization-driven topological insulator transition in a GaN/InN/GaN   quantum well
  Topological insulator (TI) states have been demonstrated in materials with narrow gap and large spin-orbit interactions (SOI). Here we demonstrate that nanoscale engineering can also give rise to a TI state, even in conventional semiconductors with sizable gap and small SOI. Based on advanced first-principles calculations combined with an effective low-energy k*p Hamiltonian, we show that the intrinsic polarization of materials can be utilized to simultaneously reduce the energy gap and enhance the SOI, driving the system to a TI state. The proposed system consists of ultrathin InN layers embedded into GaN, a layer structure that is experimentally achievable. 
M. S. Miao, Q. Yan, C. G. Van de Walle, W. K. Lou, L. L. Li, K. Chang
cond-mat.mtrl-sci cond-mat.mes-hall