Anisotropic surface transport in topological insulators in proximity to a helical spin density wave

Abstract

We study the effects of spatially localized breakdown of time reversal symmetry on the surface of a topological insulator (TI) due to proximity to a helical spin density wave (HSDW). The HSDW acts like an externally applied one-dimensional periodic(magnetic) potential for the spins on the surface of the TI, rendering the Dirac cone on the TI surface highly anisotropic. The decrease of group velocity along the direction $\hat{x}$ of the applied spin potential is twice as much as that perpendicular to $\hat{x}$. At the Brillouin zone boundaries (BZB) it also gives rise to new semi-Dirac points which have linear dispersion along $\hat{x}$ but quadratic dispersion perpendicular to $\hat{x}$. The group velocity of electrons at these new semi-Dirac points is also shown to be highly anisotropic. Experiments using TI systems on multiferroic substrates should realize our predictions. We further discuss the effects of other forms of spin density wave on the surface transport property of topological insulator.

8 pages, 8 figures

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Cited by in corpus (7)

• Transport in three-dimensional topological insulators: theory and experiment
• Spin-helical transport in normal and superconducting topological insulators
• Band structures of bilayer graphene superlattices
• Off-resonant light-induced topological phase transition and thermoelectric transport in semi-Dirac materials
• Power law decay of local density of states oscillations near a line defect in a system with semi-Dirac points
• Topological insulator in a helicoidal magnetization field
• Electrical probe of spin-spiral order in quantum spin Hall/spin-spiral magnet van der Waals heterostructures