A Topological Insulator Surface under Strong Coulomb, Magnetic and Disorder Perturbations
Topological insulators embody a state of bulk matter characterizedby spin-momentum-locked surface states that span the bulk bandgap. This highly unusual surface spin environment provides a rich ground for uncovering new phenomena. Understanding the response of a topological surface to strong Coulomb perturbations represents a frontier in discovering the interacting and emergent many-body physics of topological surfaces. Here we present the first controlled study of topological insulator surfaces under Coulomb and magnetic perturbations. We have used time-resolved deposition of iron, with a large Coulomb charge and significant magnetic moment, to systematically modify the topological spin structure of the Bi2Se3 surface. We observe that such perturbation leads to the creation of odd multiples of Dirac fermions and that magnetic interactions break time-reversal symmetry in the presence of band hybridizations. We present a theoretical model to account for the observed electron dynamics of the topological surface. Taken collectively, these results are a critical guide in controlling electron mobility and quantum behaviour of topological surfaces, not only for device applications but also in setting the stage for creating exotic particles such as axions or imaging monopoles on the surface.
L. A. Wray and S. Xu and Y. Xia and D. Hsieh and A. V. Fedorov and Y. S. Hor and R. J. Cava and A. Bansil and H. Lin and M. Z. Hasan, "A Topological Insulator Surface under Strong Coulomb, Magnetic and Disorder Perturbations," Nature Physics, vol. 7, no. 1, pp. 32-37, Nature Publishing Group, Jan 2011.
The definitive version is available at http://dx.doi.org/10.1038/nphys1838
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