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(Color online) Terahertz-magnetodielectric effect in TbMnO3 crystal. Real part and imaginary part of the a -axis dielectric constant in TbMnO3 as a function of frequency. The external magnetic field is parallel to the c axis and the ac electric field (E) parallel to the a axis. The insets show schematically the (B, T) phase diagrams of the TbMnO3 crystal, where B is the magnetic flux density of external static magnetic field and T the temperature. Such magnetodielectric effect is the base of possible absolute and tunable gap in our 2D example.
(Color online) TE-mode photonic band structure along high symmetry lines (Γ-X-M-Γ) in the Brillouin zone with an external static magnetic field of 8/0 T. The inset shows the square lattice with the parameter ∼ . The third PBG has contributions to absolute and tunable PBG.
(Color online) TM-mode photonic band structure. The second PBG appears for absolute and tunable PBG.
(Color online) Absolute gap of the band structure without the external static magnetic field. The dashed lines are the TE-mode photonic band structure and the dotted lines are the TM-mode one. The upper insets show the electromagnetic intensity distribution of the gap bottom or top at the high-symmetry point , which indicates that the absolute and tunable PBG is due to the Mie resonance. That is, the tunable and absolute gap is related to the EM absorption of a single cylinder of the TbMnO3 crystal itself. The lower inset shows the gap-to-midgap-frequency ratio as a function of radial contrast in an external static magnetic field of 8/0 Tesla.
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