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Paper   IPM / Nano-Sciences / 17008
School of Nano Science
  Title:   Optical signature of magnetoelectric polarizability of topological insulators
1.  Mahdiyeh Sadrara
2.  MirFaez Miri
  Status:   Published
  Journal: Phys. Rev. B
  No.:  1
  Vol.:  105
  Year:  2022
  Pages:   165139
  Supported by:  IPM
The discovery of topological insulators has opened a new chapter of condensed matter physics. Recently, several experiments have confirmed that the magnetoelectric susceptibility of a topological insulator with time-reversal symmetry is quantized in terms of the fine-structure constant. To realize such measurements, a number of challenges have been overcome; particularly, high-precision time-domain terahertz polarimetry is devised. Here an experiment is proposed to observe the topological magnetoelectric effect. Based on the generalized multisphere Mie theory, it is shown that the optical activity of a cluster of topological insulator spheres elevates as metal spheres are deliberately brought near to them: The destructive interference of fields of the induced electric dipoles allows fields of the induced magnetic dipoles, which originate from the topological magnetoelectric effect, to play a prominent role. For example, for clusters of Bi2Se3 and InSb spheres, the elevated azimuth and ellipticity angles are about ±20 . Such a giant optical activity serves as an optical bridge to the determination of the fine structure constant.

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