Strong nonreciprocal radiation in magnetophotonic crystals.

• The magnetophotonic crystals are proposed to realize strong nonreciprocal radiation at small angles. • The strong nonreciprocal radiation is attributed to the excitation of Tamm plasmon polaritons. • The distribution of magnetic field is studied to reveal the underlying mechanism. • The proposed structure in this work is promising to be used for verifying the Kirchhoff's law for nonreciprocal materials. Kirchhoff's law plays a vital role in radiation heat transfer, which has been recently generalized to hold for both reciprocal and nonreciprocal materials. However, the verification of the generalized Kirchhoff's law for nonreciprocal materials in experiment has not been reported. Previous proposed structures could only obtain strong nonreciprocal radiation at large angles, which were not favorable in experiment. Here, we proposed magnetophotonic crystal to realize strong nonreciprocal radiation at small angles. The numerical results show that strong nonreciprocal radiation can be obtained at angle of incidence of 30o, which is much smaller than the typical angle of 60°. The distribution of magnetic field is used to reveal the mechanism, and it indicates that the enhanced nonreciprocity is attributed to the excitation of Tamm plasmon polaritons. We believe such magnetophotonic crystal is promising in verifying the Kirchhoff's law for nonreciprocal materials. [ABSTRACT FROM AUTHOR]