Publication Date

6-6-2016

Document Type

Article

Department

Physics and Astronomy

Disciplines

Condensed Matter Physics

Publication Title

Physical Review B

Abstract

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.

Keywords

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

Comments

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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