Tunable and absolute electromagnetic vacuum in two-dimensional photonic-band-gap Based on multiferroic materials

When multiferroic terbium manganite (TbMnO₃) crystal cylinders are periodically arranged in a square lattice, the resulting two-dimensional (2D) system exhibits photonic band gaps (PBGs). The absolute PBG originating from the Mie resonance is modulated from closed to open by applying an external static magnetic field, which is attributed to the electromagnon depression of the dielectric constant by the rearrangement of antiferromagnetic order. Tunable electromagnetic band structure may be realized by controlling the magnetic transition of manganese spins in TbMnO₃.The authors are grateful for financial support from the Outstanding Foundation of NJUST, the NJUST Research Funding (No. 2010ZDJH06), the National Natural Science Foundation of China (Grant Nos. 11004106, 50672034, 50832002, and 50901042), and the State Key Program for Basic Research of China (Grant Nos. 2009CB623303 and 2009CB929501)