Giant enhancement of nonreciprocal thermal radiation by the position of Weyl nodes in momentum space

Abstract

The anomalous Hall effect of Weyl semimetals is attractive in asymmetric transmission and thermal radiation. The effect of the position of Weyl nodes on nonreciprocal thermal radiation has not been fully investigated. To address this challenge, the nonreciprocity of the twisted Weyl semimetals for different polarization states is investigated. By the twisted angles between two Weyl nodes, strong nonreciprocity can be observed for both transverse electric and transverse magnetic polarizations at an incident angle of 30°. In addition, the dual-polarized nonreciprocity is significantly enhanced by changing the position of the Weyl nodes in momentum space. The significant difference between absorptivity and emissivity originates from the contribution of the two distinct Fabry–Pérot modes. Further calculating the polarization conversion, the nonreciprocity primarily arises from the significant difference in co-polarized reflectivity components. Detailed investigations reveal that the dual-polarized nonreciprocity at appropriate twisted angles remains, when the momentum separation of the Weyl nodes follows an arbitrary direction. These findings hold significant values to develop efficient nonreciprocal thermal emitters.