Excitons and Optical Absorption on the Surface of a Strong Topological Insulator with a Magnetic Energy Gap

Abstract

We present a theoretical study of interacting electron-hole pairs located on a magnetized surface of a strong topological insulator (TI). The excitonic energy levels and the optical absorption on such surface display unique and potentially measurable features such as (i) an enhanced binding energy for excitons whose total angular momentum is aligned with the magnetic exchange field, (ii) a stark dependence of the optical absorption on the direction of the magnetic exchange field as well as on the chirality of the incident light, and (iii) a tunable center-of-mass motion of spinful excitons induced by particle-hole asymmetry in the exchange field. Our predictions are relevant to surfaces of magnetically doped TIs or surfaces coated with magnetic films, in addition to TI nanowires placed under longitudinal magnetic fields.

12 pages and 9 figures. Revised version, accepted in Phys. Rev. B

References in corpus (5)

• Topological Field Theory of Time-Reversal Invariant Insulators
• Direct Evidence for the Dirac-Cone Topological Surface States in Ternary Chalcogenide TlBiSe2
• Tunable Excitons in Biased Bilayer Graphene
• Berry Phase Effect on Exciton Transport and Bose Einstein Condensate
• Spin Hall Effect of Excitons

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• Observation of room temperature excitons in an atomically thin topological insulator
• Exchange-Driven Intermixing of Bulk and Topological Surface State by Chiral Excitons in Bi2Se3
• Exciton absorption spectra in narrow armchair graphene nanoribbons in electric fields
• Excitonic effects in time-dependent density functional theory from zeros of the density response
• Quantum Internal Structure of Plasmons
• Sommerfeld enhancement factor in two-dimensional Dirac materials
• Hybrid dark excitons in monolayer ${MoS}_2$
• Unconventional quantum Hall effect in Floquet topological insulators