Publication Date


Document Type



Physics and Astronomy


Condensed Matter Physics

Publication Title

Physical Review B


We consider the proximity effect between Dirac states at the surface of a topological insulator and a ferromagnet with easy plane anisotropy, which is described by the XY model and undergoes a Berezinskii-Kosterlitz-Thouless (BKT) phase transition. The surface states of the topological insulator interacting with classical magnetic fluctuations of the ferromagnet can be mapped onto the problem of Dirac fermions in a random magnetic field. However, this analogy is only partial in the presence of electron-hole asymmetry or warping of the Dirac dispersion, which results in screening of magnetic fluctuations. Scattering at magnetic fluctuations influences the behavior of the surface resistivity as a function of temperature. Near the BKT phase transition temperature we find that the resistivity of surface states scales linearly with temperature and has a clear maximum which becomes more pronounced as the Fermi energy decreases. Additionally at low temperatures we find linear resistivity, usually associated with non-Fermi liquid behavior, ho wever here it appears entirely within the Fermi-liquid picture.


BKT transition, Dirac fermions, Proximity effect, Ferromagnets, Topological insulators


This article originally appeared in Physical Review B, volume 93, issue 24, 2016, published by the American Physical Society. ©2016 American Physical Society. The article can also be found online at this link.

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