Influence of Helical Spin Structure on the Magnetoresistance of an Ideal   Topological Insulator
  In an ideal topological insulator, the helical spin structure of surface electrons suppresses backscattering and thus can enhance surface conductivity. We investigate the effect of perpendicular magnetic field on the spin structure of electrons at the Fermi energy and calculate a magnetic-field dependent topological enhancement factor for different disorder potentials, ranging from short-range disorder to screened Coulomb potential. Within the Boltzmann approximation, the topological enhancement factor reaches its maximum value of 4 for a short-range disorder at zero magnetic field and approaches a value of 1 at high magnetic fields independent of the nature of the disorder potential. 
Teoman Ozturk, Richard L. Field III, Yun Suk Eo, Steven Wolgast, Kai   Sun, Cagliyan Kurdak
cond-mat.mes-hall