  We propose a model of three-dimensional topological insulators consisting of
weakly coupled electron- and hole-gas layers with Rashba spin-orbit interaction
stacked along a given axis. We show that in the presence of strong
electron-electron interactions the system realizes a fractional strong
topological insulator, where the rotational symmetry and condensation energy
arguments still allow us to treat the problem as quasi-one-dimensional with
bosonization techniques. We also show that if Rashba and Dresselhaus spin-orbit
interaction terms are equally strong, by doping the system with magnetic
impurities, one can bring it into the Weyl semimetal phase.
